To add multiple users at once, go to Space Settings > User, and under "List of Users", click “Manage Users on Nulab Apps”.
Then, click the icon to the right of the organization name and select "Bulk members invite (CSV)". Then, follow the instructions on the following page.
Fill out and upload the CSV file of user information.
Please doublecheck the contents of the CSV file and click the "Add users" button if all of the details are correct.
The users will be added to your space, and each user will receive email instructions on how to log into Backlog with their passwords.