Yoxel Sync will be accessing your accounts (Teamwork, G Suite, Office 365, MS Exchange) remotely and needs your authorization for that. Teamwork account authorization is API token based.

1. Start Yoxel Sync app from 'My Profile' -> 'Integrations' tab:

2. Expand your Teamwork service/connector to confirm that your portal url and API token are already entered.
Usually the url and the token will have been auto populated for you. If the token field is empty see Looking up your Teamwork API token article.  Check what you'd like to sync 'Calendar' (for calendar events and milestones), 'Tasks'. Then click 'Save'.