When trying to run the new-TestCasConnectivityUser.ps1 script the latter might fail with the following error
CreateTestUser : Mailbox could not be created. Verify that OU ( Users ) exists and that password meets complexity requirements.
The first thing you need to do is making sure that the password does meets complexity requirements however if you did and still having the failure you most probably have multiple OUs with name “Users” and that is why the script is failing.
The solution for this is to specify the OU in the command by running the following
get-mailboxServer | .\new-TestCasConnectivityUser.ps1 -OU domain.com/users