Replying to the suggestion that I contact the company responsible for the channel.
The problem is that it's not clear who's responsible for TLA Gay Movies (TGM). Its website is copyrighted by Ravana LLC, which I believe is associated with TLA Releasing, maybe as its parent company. There's no contact information on the site.
However, according to the TLA Video customer service rep, Roku takes care of billing for TGM and those accounts are separate from TLA Video accounts. She wasn't able to see the account I set up on the TLA Gay Movies channel, and couldn't help me with my login problem. See my other post for the solution.