NOTE: The instructions listed below are the same for both Salesforce Classic and Lightning users.
1 - Log in to your Salesforce instance as a System Administrator.
2 - Click 'Setup' in the uppermost navigation panel.
3 - Under the ‘Administer’ heading, click 'Manage Users' and then ‘Profiles’.
4 - Click the Profile Name of the SFDC User who will OAuth with Terminus Hub.
5 - Under the 'System' heading, click 'System Permissions'.
6 - Verify that the box for 'API Enabled' is checked. If it is not, check the box.
If you need further assistance, please contact firstname.lastname@example.org.