First, i would go watch the new documentary on Netflix, that answers a lot of questions.
So, like a lot of UofM fans, he was weird in his fandom. A Walmart Wolverine. He always wanted to coach football, that was his dream. He went to the Naval Academy (military), because that's what all great coaches did in the past. He got his foot in the door by offering to help the coaching staff with anything they needed. His first part of the Navy team was to decipher signals (sign steal). He was really good at it, like really good. In the military for Navy, he was an intelligence guy.
He then learned that there is an underground sign stealing brotherhood with all the signal chasers. He learned what they were doing and decided to be better than them.
After graduation he started working for UofM football. he developed new systems to decipher signals. He was, for a lack of a better phrase, highly committed to making sure UofM Football was the best.
At the same time, as a staff member, he got dirt cheap tickets (sometimes free) that he could give to family and friends, or sell for a profit.
Things you can do to not break any sign stealing rules in the NCAA:
1.) Be on the field and watch signals in person and try to decipher them live during your game.
2.) Record and watch any televised film, try to decipher signals that way.
3.) Have third parties tell you what the opposing signals are, write them down, and remember them. (Secret underground sign stealing fraternity)
What you cannot do, is go to an opposing teams games and record the signals yourself.
The gray area is, can you have family or friends do that for you. it is NOT black or white, it is very muddy. Logically, you shouldn't be able to do that, but what if you have an overzealous Walmart Wolverine friend that texts you their recording, thinking they are helping?
TL;DR, Connor was very good at his job, he was obsessed with UofM Football from a young age. He gave tickets away to family and friends who recorded parts of games, and sent the to Connor. Connor states he already knew all those signals, so it was no big deal. You cannot go to opposing games and record their signals yourself, it is a gray area for other people to do it for you.
Draw your own conclusions.
Connor denies he was on the CMU sideline to record MSU's signals. World famous egomaniac El Presidente claims Connor told him it was him on the sideline. Connor and the guy on the sideline, do look similar, but nothing definitive proves it was him.
I am a CMU alum, coached College Hockey at MSU, I cheered when UofM when the Natty, I've always rooted for MSU to beat UofM in football, because my Dad went to UofM, but most of our family went to MSU.