Follow these steps to upgrade your account to the new V3 API:
1). Login to your account at https://hubspot.
2). Click "My Settings"
3). Click "Connection Details"
4). Click the Orange "Authorise WorkflowMax/Xero Practice Manager Access" button
5). Follow the directions in the popup.
6). Allow the app to connect
7). Once this is done it should take you back to the "My Settings" page.
After these steps are complete please allow up to 24 hours for the migration to take place. It usually takes a lot less time for the migration to occur, but that's a safe time to check and make sure everything is good to go.