QBO Accountant is a different portal. Regular QB Online users have a sign in. The Accountant portal is where you would see all the QBO companies you are "invited" as the Accountant. Think of it as an Umbrella.

"Is there a place/link/chart to check?"

At the QBO forum, and at the first link I gave: "

Precision without the pain

ProConnect integrates with QuickBooks Online Accountant for end-to-end accuracy with less effort. Pivot between client books and taxes with one login to save time in your busiest season."

And at the second link I gave, you see how it functions.

Right here, you are asking Peer tax preparers. This is not Sales not Intuit Customer Support.