As you probably know as a Smartsheet user, these regions cannot be mixed, so we have to know which at which region we must activate the request for you.
Check your smartsheet URL in your browser to be sure:
https://app.smartsheet.com = default Smartsheet region
usually US, KSA, Australia, Africa etc.
either
https://app.smartsheet.eu = EU Smartsheet region
usually DE / NL / BE / FR / etc.
Still not sure?: please select 'not sure'. We will contact you.