How to properly link an existing personal Facebook ad account to a business manager?

Question

Facebook

Hello.
Can you please tell me how can I link an existing Facebook advertising account to a business manager so that he does not ask for some kind of initial payment to start? Since I want to run ads based on numbers, and without a connected business manager, this is simply impossible to do!

Here's what it displays when you try to add a new custom audience (to add a file with a database of numbers)

Those. I have to spend some amount of money (it’s also not clear how much) and only then can I add a file with an audience?!
Or can this new ad account be linked to another one of my Business Managers that has already been spent?