Go to Settings → Integrations → Google Business Profile and click Connect. You'll be asked to sign in with the Google account that manages your listing and grant Sadakom read/reply access to reviews.
If you manage multiple locations under one Google account, you'll be asked to pick which listing to connect to this Sadakom business — connect each branch separately if you run more than one.
If your business doesn't appear in the picker, it usually means the signed-in Google account isn't listed as a manager on that profile yet — add it from Google Business Profile settings first, then retry the connection.