Klonup supports Smartsheet accounts in both official regions: the US and Europe (EU).
To connect your account you need a personal Smartsheet API Key, which you generate from your Smartsheet profile and paste in when creating the Connection in Klonup.
Recommendation: use a Smartsheet account dedicated to backups, rather than an individual employee's personal account. That way you avoid depending on one specific team member, and you avoid backup copies of the protected workspaces piling up in their personal account, mixed in with the workspaces they actually use day to day.
If you need to switch Smartsheet accounts or regions later on, you don't need to create a new Connection: you can update the API Key on your existing Connection instead.