Get a customer
$customer = Get-PCCustomer -tenantid '<tenant id GUID>'
Create a customer user
$password = '<password>'
$passwordSecure = $password | ConvertTo-SecureString -AsPlainText -Force
New-PCCustomerUser -tenantid $customer.id -usageLocation '<country code>' -userPrincipalName '<upn>' -firstName '<first name>' -lastName '<last name>' -displayName '<display name>' -forceChangePassword $true -password $passwordSecure