You could setup a user account like the share you’re describing. There’s a setting to prevent the user from changing their password.

Just pass out those credentials to anyone you want to collaborate with; they don’t need their own individual accounts.

I use https://filebrowser.org/ for this.

Nice lightweight filebrowsing/sharing with user management. Users can have their own dedicated directories, or collaborate.

You can also create share links that allow anyone with the link to view/download files. Optionally password protected.

Here’s a demo you can mess with: https://demo.filebrowser.org/ User: demo Pass: demo