Contracts for Salesforce integrates with your Salesforce org using the login credentials of a user of your choice. The user should have sufficient permission for Contracts for Salesforce to modify records in Salesforce. While logged in as the selected user, click Connect and accept the OAuth prompt. When returned to the page you should see the status change from Not Connected to Connected. You can reconnect troubleshoot or change the connected user.
If the Connect or Reconnect option is not available, your current user does not have the required permissions to use Contracts for Salesforce.