Welcome to the Make community!
Yes, you can definitely have a global custom app invite link like this:
https://make.com/en/hq/app-invitation/be1ae21f84e234e707093a0ae1658770
See it in action here: [Free App] My Toolbox of Useful Modules
Hope this helps! Let me know if there are any further questions or issues.
— @samliew
P.S.: investing some effort into the tutorials in the Make Academy will save you lots of time and frustration using Make!