Hi Erika,
Using the link below will allow you to complete the registration process for a user, as long as you have their correct email address. You will be able to enter their name and create a password for them, which they could change later if they wish.
https://yourdomain.quickbase.com/db/main?a=regJust change 'yourdomain' to match your actual quickbase domain and it should take.
Let me know how this works for you!
Thanks and good luck!