Business Manager is free to use. To start, first make sure that you have a personal Facebook account to confirm your identity.
Next, sign up for Business Manager:
Note: If you don't yet have a Page for your business, create one.
If you're a partner or work on ad accounts or Pages on behalf of another business, the business invites you to access specific Pages or ad accounts. You can also request access to their Pages and ad accounts.
Have more assets to add to Business Manager? Learn how to add Pages and ad accounts to Business Manager.