Thanks @Bastien_Siebman for the ping!
Hi Phillip! I’m the founder of Instagantt.
You can have only 1 admin under your subscription, and Instagantt inherit all the rights your users have in Asana. If you have a project that don’t want to be modified by anyone else, you can create a Private Project, add it to your Instagantt account, and then share with your people a Public Snapshot, which is a read-only link you can share with anyone without the need of having an Instagantt account.
Please let me know if this helps!