To add/invite users to Ignite, follow the three steps described in this guide.
To begin, click "Data & Configuration" in the lower left side of your screen.
Enter Settings, and then navigate to the Users & Roles section in the menu.
From here, you can invite new users via email by pressing the Invite users button in the top right.
FAQ
Q: I successfully invited the person, but they cannot find the email in their inbox.
A: Ask the person to check their spam/junk inbox, as it might end up there if they have strict filtering on their inbox.
Q: The person cannot find the email, and it is not in the spam/junk inbox either. What might have happened?
A: Try to invite them again, there might have been a typo in the email address.
Q: I get an error stating that "Something went wrong" when attempting to invite a new user, what should I do?
A: If you get errors when attempting to invite a new user, check that the email is correct and send a new invite after waiting a couple minutes.