Thanks guys, that makes a lot of sense and I had not thought it through about the many-many being the blocker, and why.
The reason for Many-Many between Users and Providers is that someone might work at more than one provider, or own more than one provider.
So I’m going to experiment a bit with drop downs as the Adalo guy suggested and see what I can do to get things to work the way I want. The insight and advice above certainly give me the right path and understanding to make this work.
Thinking about this from a higher level it makes me think it might be a neat feature for Adalo to have a little popup when going through the data links that could show why something isn’t clickable (ie M-M so can’t pick one, not associated etc) to give people some guidance (especially new creators).