As an Admin, you have the ability to reset user accounts. This procedure is a helpful first step when troubleshooting login issues.
From the Admin portal, select Users > All Users:
Use the search bar to find a specific user. When you find them, click the User Details icon next to their name:
On the user details page, click Unlink Login:
Once you've unlinked your user, you can re-invite them by clicking the Invite User button:
The user will receive a new invitation by email, from which they can select a new login password.