Novices and newbies discussion

My girlfriend and I have been considering chastity for a while, but I recently purchased the Mancage 02 from Extreme Restraints. Once we got it home, fiddling with assembly was one thing, but putting it on has taken several attempts. The ring that encircles my balls just won’t seem to fit right. I’m using the largest size available, which seems slightly larger than average based on what I’ve read, yet when I slide into it, it feels quite constricting. I understand restriction is part of the deal, but mine gets so tight it turns red. What options do I have? Are there other cages with a roomier ring that might work better?