Registering Micro Entreprise with “attestation de décision favorable”

There have been similar questions around this, but I thought I’d better double check.

I’m a Canadian citizen and arrived in France six months ago as the spouse of an EU citizen. For immigration, I requested a “titre de séjour” and have received an “attestation de décision favorable” along with a “Nº étranger”, yet I’m still waiting for the actual “carte de séjour” to be issued.

As we’re still in the process of getting settled and looking to find the suitable property for purchase, both my spouse and myself are deemed “inactif” at the time.

After three months of living here, I registered with CPAM and they asked for documents from Canada, more specifically a form “SE 401-03”. They didn’t tell me where I could obtain that form, nor what kind of information this form would contain, only hinting at “social insurance confirmation”. So I contacted authorities in Canada, and they wouldn’t know either.

CPAM suggested to contact RAMQ, the provincial health authority in the province of Quebec, yet I lived in Alberta and British Columbia and RAMQ in Quebec doesn’t even know that I exist.

In essence, I’m stuck in the process and therefore decided to look into registering a Micro Entreprise. So at the moment I have two questions:
a) can I even register a Micro Entreprise with the “décision favorable” and Nº étranger, or do I have to wait for the “Carte de séjour”?
b) how should I inform the authorities that there is an open file with CPAM, requesting documents from Canada that are un-obtainable?

Thank you!