After a server to cloud migration, the admin managing the migration needs to inform their team to 

1. visit https://id.atlassian.com/login/resetpassword
2. request a password reset
3. Go to the inbox
4. click on a link to setup a password.
5. then end-users can login.

With this flow, the on-boarding of end users takes a few clicks for each users.
It would be great if any of the following were possible

1. Admins could set a default password for all their users
2. When users were added as a part of the site-import, send invitation emails to all users
3. provide a REST endpoint so that admins can write a script to trigger the password reset requests.

Note - In Atlassian Access, this is possible how it requires additional steps.