Resend a user's password in Office 365 - Admin Help
This article explains how to resend the notification email to a new user in Office 365. You do this by resetting the user's password.
You must be an global admin or password administrator to perform these steps.
On the Active users page, select the user and then select Reset password.
Follow the instructions on the Reset password page to auto-generate a new password for the user or create one for them, and then select Reset.
Enter an email address the user can get to so they receive the new password, and follow up with them to make sure they got it.