Hello everyone, RomM creator here!
First of all, thank you all for giving RomM an opportunity and showing interest on it!
Said that, I am sorry for the current bad support of unraid, I don't have any machine to test it right now so I am blind on this.
In any case, I will take note, because I know that the hardest entry point for new users is the twitch api keys and the config.ym file. We have plans to auto-generate this file if the user don't generate it manually at the setup of RomM and in the future that file will be managed in the front aswel to be easier for the users.
About the URL field when creating the twitch api keys, just put "http://localhost" and it should works. You have a section in the RomM's wiki with some tips and troubeshooting: https://github.com/zurdi15/romm/wiki/Troubleshooting
I will add a customized twitch api key generation guide for new users.