[Membership 2 Pro] How to assign a Membership to an admin user

I have a multisite installation. I don't want individual subsites to be able to install addons to plugins, or to change some settings, hence I want to limit the options of the admin user.

I cannot do that with Membership 2 Pro, as it doesn't allow assigning a membership to an admin user.

I have tried setting up a new user role with user role editor plugin, and assigned that new role to the administrator, but still it recognizes the user as WP administrator and doesn't let assign a membership.

How to limit the options of an admin in the admin area?