Connect-PnPOnline -Url https://testdomain.sharepoint.com/sites/test1
-PnPO365ManagementShell -LaunchBrowser

$username = "test@exemple.com"
$password = "password"

$cred = New-Object -TypeName System.Management.Automation.PSCredential -argumentlist $userName, $(convertto-securestring $Password -asplaintext -force)

Connect-SPOService -Url https://testdomain-admin.sharepoint.com -Credential $cred