If you need to add Digivizer, or any business, to your Facebook Business Account, please follow the following steps.
When you add a partner to your Business Manager, you can grant access to different assets and assign specific permission levels.
How to give a partner access to assets in your Business Manager
To add partners or agencies to your business:
Go to Business Settings.
Below Users, click Partners.
Click + Add.
Select Give a partner access to your assets.
Enter the Partner Business ID you want to add and click Next.
On this screen, you can add partners to multiple assets. Choose a type of asset in the first column. Select the assets you want to add your partner to in the second column. Assign a role for your partner in the third column. Repeat these steps until you've chosen roles for all of the assets you want to assign.
Click Save Changes.
Your partner can now see the assets you assigned to them in Business Manager.
Also read this article here: https://www.facebook.com/business/help/1717412048538897?id=2190812977867143