Important. You can not configure auxiliary backup accounts for on-premises Microsoft SharePoint organizations. The entire security group will be granted the Site Collection Administrator role, which means that each user in this group will be granted this role as well, regardless of what users have been added with the SecurityGroupMember parameter. The role, however, can only be granted if you ...
You can go back to the same steps we performed in the previous section and add you admin user under the site adminstrators section in the SharePoint Admin Center. Again the path is User Profiles>Mange User Profiles>Manage Site Collection Owners. Perform for all users