Are you trying to do multiple offers and requests for each specific fandom? This is different from a lot of other exchanges that match on fandoms AND ships (or additional tags, or characters, or whatever). Matching for Remix Revival is for one medium (fic remixed as art, fic remixed as fic, etc.) and one fandom, so all of the fandoms you want should be combined into one request. The maximum limit is 2 requests to allow people to request up to 40 fandoms total (the limit on AO3 for request is 20 fandom tags), and/or to specify that they want certain fandoms remixed in certain mediums. (So your Request 1 might be all the fandoms you want remixed as art, while Request 2 might be the ones you want remixed as fic, or some other combination like that.)

It will work the same with offers: you'll combine all your fandoms into one. You'll be matched on 1 medium (fic remixed as fic, fic remixed as art, etc etc) + 1 fandom. If you look at the request summary you can see examples if that helps. Does that make sense?