A GSuite admin can install and approve draw.io for Gsuite on behalf of all users on a domain. Firstly, navigate to https://admin.google.com and log in. Click the "apps" section:
Followed by "marketplace apps":
In the next page click the "+" symbol towards the top-right:
In the dialog that appears search for "draw.io diagrams" and click on the draw.io box that appears. In the listing for draw.io click "domain install":
and accept the terms and permissions presented.
If you want to have the footer removed in the draw.io editor for all users, go back to the "marketplace apps" section, click on "draw.io", click "edit service" and send us a screenshot of the resulting page by email to firstname.lastname@example.org, that screenshot must include the GSuite domain at a resolution that can be read: