Applying for healthcare - who do I contact?

I have a question but also want to share my experience so people don’t make the same mistake as me!

I am a UK citizen who arrived in 2020 and now have 5-year residency and work partly as auto entrepreneur.
When I applied for AE/ME status I made the mistake of putting my domiciliation address for my business (in Paris) and personal address (I actually live in Montreuil so a different prefecture to my docimiliation address).
I then received a letter from Ameli in Paris asking me to send in my documents to apply for my healthcare.
I sent this in and waited a few months then contacted them and they said they hadn’t received anything.
I resent the requested documents and they then replied within a couple of weeks asking me to send in the documents with my updated address.
I called to clarify and as I suspected, they said that because the address on my Carte de Sejour was in a different prefecture to the one I had applied for AE status with then I needed to change my address in my AE account and reapply. I can see now why I needed my actual personal address in my AE application!
My personal address in AE is now showing correctly and…

My QUESTION:
Which form do I complete and who do I sent it to, to apply for healthcare? Is it the usual Ameli form here: https://www.ameli.fr/sites/default/files/formulaires/168/s1106_-_demande_puma_-_assurance_maladie.pdf sent to Amele in my prefecture? I have read somewhere here about having to apply to RSI rather than CPAM but I can’t figure out what that means.
The previous form was just a request from Ameli Paris but it didn’t have an application form as they already seemed to know I had applied for AE.
Sorry for the long post, I wanted to be clear of my situation!
Thanks!