Dude I've got 2 words for you with this, "move on".
I don't even know where to begin where you went wrong, but that being said I'll try and help a little. This is just my opinion, others may have their own views but this is my verdict.
For a start your mentallity is defeatist
"I am pretty much used to let downs from girls"
Why should you have to get used to it?! Everytime I get let down/shot-down/flaked on it only spurs me on to improve at what I'm doing. That's what you should take from dissapointment, lessons. Post here, realise what you did wrong, correct it for next time.
As for the bit just both that lines I quoted from you where you said you took it lightly, clearly you didn't, at least not at your core. I'll break it down as to why you shouldn't have felt the need to FB them that first message.
It was no big deal, your friend was the one arranging the meet up, you were just tagging along, for whatever reason they didn't come and meet you guys, they stayed where they were, I'd bet they would have come over to you guys had your friend 'performed' better before hand. As opposed to the girls WANTING to hang out with you guys, it appears they were just willing to.
Next is the likely reason why your friend didn't perform well. You say he has a crush on one of them but won't go and look for them. I don't think your friend understands quite what he did here.......if you make the effort to go out of your way and go to the park to meet up with someone, you are going looking for them. Doesn't matter what happens when you get there, you've already shown your intent by going all the way there, by not just going and meeting up with them it's obviously a bad attempt at playing hard to get, which I'm sure they recognised. He's signalling to them that he's interested, but not man-enough to go in take the bull by the horns and fucking get shit done. There is no reason why you guys couldn't have met up with these girls then bounced them to another location, re-affirming your dominant status as men.
Now we come to your message.......
We made the effort and came over at museum gardens instead of the original promised place. You should have made the effort to move your butts 20 meters were we were, just out of courtesy!
You're whining little a little girl that they didn't come meet up with you, you say they couldn't have made the effort to move 20 meters, I'm sure you guys travelled a lot further than that to get to the park, so what's the point of trying to win 'hard to get' points by now?
No offence but your act proved my theory right. Girls are not yet women before they reach their 25th year. Which is in a way bad, because I would like to know u girls a bit better
This is pretty much always going to be taken as an insult, you are questioning their maturity and in-part, their intelligence (by infering they aren't grown up).
Maybe another time, or maybe not! Your call!
Can you hear that "Help us please we're dying down here" that's the sound of your balls dissapearing.
So let's recap on that, you've whined about them not hanging out with you, insulted them, then given them the option to tell you where to stick it.
Try to put yourself into the mind of a woman, does this person sound attractive to you?
I won't go through your next few messages in as much detail as they are essentially more of the same. One thing I think you need to grasp which is evident in your follow-up messages; is use of emotes (smilies) when you're saying negative things:
I just dont get why u didnt move to were we where at!! 
You're expressing displeasure at their actions then putting some happy faces after, it's completely in-congruent with what you're saying and again says to her "I'm annoyed about you flaking on me but I'm willing to forgive you if you'll give me chance pretty please with sugar on top because I don't have any other options"
Dude I'm gonna give you an example from myself that I did yesterday with a girl. I met her in the street about 3/4 weeks ago, got her number after just a couple of minutes of talking and have since been trying to get her out on a date, I've known that she is studying hard for her final exams for a law degree since meeting her so knew this would be tough, however last friday I bumped into her when I was on a night out and didn't even recognise her. She was going home, so the next day I told her "we're going out this week" she didn't respond well enough for my liking, so yesterday I text her saying something along the lines of "I didn't take your number just to be phone buddies, I'm aware it was bad timing for us to meet but it's just been too long now so it was a pleasure meeting you and good luck with your exams".
She responded with a chorus of "I'm really sorry I have been so boring blah blah blah blah blah, hopefully I'll see you around again sometime soon!
" I simply replied with essentially the same message again. But if you see, I'm not being insulting, I'm not being needy, I'm not whining. I'm explaining to her that it's been too long for us to have not met up again after meeting and I don't see a reason to keep in touch unless we were to arrange to meet up again, she intern apologised.
Anyway I've ranted long enough, like I said maybe someone else with have a different point of view but that's mine so glean from it what you will.
CHAT
Had some girls that approached me but I failed to realise their signals and missed my chances :/
