I am trying to assign a systemuser of my application to a Page with the Advertiser role as described in https://developers.facebook.com/docs/marketing-api/guides/smb/system-user-access-token-handling/v3.0:
curl -i -X POST "https://graph.facebook.com/v3.0/<PAGE_ID>/roles?admin_id=<USER_ID>&role=Advertiser&access_token=<ACCESS_TOKEN>"
When I try this with my data and access_token I get this error message:
(#200) Either app or user doesn't have permission to modify admins.
The problem is, that the infos provided on the info-page are very sparse and I have no clue what the required special permissions are and where to get them:
Assigning permissions to a page from the API requires special permissions. Please reach out to your Facebook rep if you require this feature.
The application currently has permissions for:
* email
* manage_pages
* pages_show_list
* publish_pages
* ads_management
* ads_read
* business_management
* public_profile
I finally found a solution to my problem.
The documentation at the The SMB Integration Playbook does not help though...
Instead you have to use a combination of two steps: