You can use an Excel spreadsheet or CSV file in conjunction with Admin Portal to perform a bulk import of user accounts using an import template. You can use a bulk import user account file can to import up to 10,000 accounts at once.
However, in most cases, you should only perform a bulk user import after you have created the appropriate roles and assigned the appropriate web applications to those roles. If you import user accounts before you have added roles and assigned applications to the roles, new users will see an empty Apps page when they log on to the Admin Portal for the first time.
For details about creating the bulk import file, see How to Bulk import user accounts.