The following is from Facebook Business Help Center
Add people to your business and grant them permission to assets in your Business Manager. These steps are for adding individual people to your Business Manager, not partners such as other businesses. Learn more about partners in Business Manager.
Before you begin
Only Admins can add people to your Business Manager.
Don't add people to your Business Manager if you don't know them. Scammers may create fake accounts in an attempt to manipulate people and businesses. If you’re unsure if a request is authentic, contact the person in the real world to confirm they initiated the request and that you’re comfortable adding this person to your Business Manager.
Facebook never asks for access to a Business Manager. If a business that claims it's Facebook asks you to add them to your Business Manager, it's not a legitimate request. We recommend that you deny the request and report it.
Third-party businesses can't get you verified: If a business claims it can help get your business verified on Facebook and wants you to add them to your Business Manager, it's a scam. We recommend that you report it. You can only complete business verification through the Business Info section of your settings. It doesn't require any specific person to have access to your Business Manager. Learn more about business verification.
Add People to Your Business Manager
To give people access to your business:
- Go to Business Settings.
- Click People.
- Click + Add.
- Enter the work email address of the person you want to add.
- Select the role Employee access.
- Click Next.
- Choose Catalogs > select your catalog > Manage Catalog.
- Click Invite.
Learn more about Business Manager roles and permissions.