How to get Acrobat Sign API application certified for multi-tenant OAuth access

Hi, I'm building a monday.com marketplace integration that connects to Acrobat Sign via OAuth (Authorization Code flow). The app is designed so that each of monday.com customers (separate organizations) will connect their own individual Acrobat Sign account to our app.

I registered my OAuth application under our Adobe Developer Console account, then tried testing the flow using a separate Acrobat Sign Business trial account under a different email, to simulate a real customer connecting their own account.

The OAuth flow returns:

error: access_denied
error_description: User cannot authorize access because it is UNCERTIFIED

Based on Adobe's Developer Terms of Use (section 20.4(C)): "You must enter into a separate written agreement with us if you wish to sell, distribute, or offer Developer Software that is designed to interoperate with Acrobat Sign API."

My questions:

1. Is this "UNCERTIFIED" error specifically tied to the certification/agreement mentioned in section 20.4(C)?
2. What's the exact process to request this certification/agreement for a multi-tenant app like ours?
3. Is this the same as, or different from, applying through the Acrobat Sign / Document Cloud ISV Partner Program?
4. Is there a way to test with a small number of pilot/beta customer accounts while certification is in progress?
5. Roughly how long does this certification process typically take?

Any guidance from Adobe staff or others who've been through this process would be greatly appreciated. Happy to share more technical details (scopes requested, OAuth flow specifics) if helpful.

Thanks!