Is it possible for a couple users to share the same exact drive space

My recommendations:

  • Make a new user and set it up with the desktop client
  • Make a basic user group and call it Collaboration
    • Add everyone to Collaboration
    • Share things with Collaboration
    • set your desktop client to accept shares of any size from Collaboration

Read the Nextcloud documentation to learn more about how things work. You’ll just not understand it until you consult the documentation, then you’ll be good to go.

Enable apps for specific groups

Read the documentation and:

Everyone - all the basic user apps
Admin
Extras

and add your various apps to these app groups.

Re-organize the top bar

Install AppOrder
Re-organize the apps in the top bar to show / hide them in a sensible manner.
Apply these settings to all of your users.

If confused, just search for the github of any particular app or search for that app’s documentation.