Pick your situation. You get the exact clicks, who has to do them (you, the client, or your CS lead), and what to check when Meta says no.
If you are not sure, ask the client to open business.facebook.com. If the only option they see is "Create a business portfolio", they have none.
614911427629287 (Influenceup Ltd). The client pastes this in Partners. Copy button lives in every partner step.
They find it in Settings, Business info, at the top. 15 to 16 digits.
Ads Manager, click the account name top left: the long number is the ID. It is also in the address bar after act=.
Open the Page, About, Page transparency. Or paste the Page URL, Meta accepts it wherever it asks for an ID.