If you have a large number of users, you can import a CSV file containing user name, email address and password. This is useful to automatically create all users in a single step.
To import all users via CSV, you need to create a CSV file with the items 'name', 'email address' and 'password' that contains all users for your company. Then you login with your admin to Tuta and go to 'Settings' → 'User management' → '...' → 'Import Users'
You can then provide the user passwords to the users, so they can log in into their individual mailboxes.