The Rangers Twitter page has 511k followers, all who would have seen the multiple posts on how to buy tickets there. The Facebook page has 647k followers who again will have seen the multiple posts on how to buy tickets there. Over 1.1M reach, and even more when you factor in multiple posts, and shared posts.
If I was to take a guess, the amount of people who don't have either of those forms of social media yet would go onto the Rangers website to see if there was tickets available for an U21 game would be less than 20 people.
The colts games have been getting roughly 1000 attendance roughly for their games so far, so even if every single one of those people didn't have social media, that is still 0.08% of the reach of the 2 social media outlets I mentioned.
And to top it all, if you go onto the Rangers website and go into the tickets section, the tickets are available there, as well as a post that someone else has highlighted!
You have chosen to "knock the club" as you put it when the club have done absolutely everything any normal person could expect them to. I don't know why you wanted to "knock the club", but it certainly can't be for anything they have, or haven't done with relation to promotion of this game.