You see the error as Insufficient access, package license is not supported if the Salesforce user that has processed the oAuth does not have access to all the V4S Mobile, Contacts, or to the Volunteer For Salesforce objects.
To fix the login issue
- oAuth: Make sure that the Salesforce user that processes the oAuth has access to all the V4S Mobile objects in Salesforce, click here to know more
- Access to Volunteer For Salesforce objects access: The oAuth user have access to Salesforce Contact and to all the objects related to Volunteer For Salesforce
- Manage Licenses List: If the Volunteer Manager/Volunteer Co-ordinator is processing the oAuth then that user should be added to the Manage licenses list. Click here to know more