Hover uses OAuth 2.0 for authentication. In simplified terms, OAuth 2.0 works to connect Hover with its user organizations by leveraging the common integration partner they share. To set up this authentication follow the steps outlined in the Getting Started Guide
For example, an integration with Zapier exists for Hover already, a company called 123Remodeling would "Allow" (one time, manually) Zapier to access 123Remodeling's data on their behalf to share to 123Remodeling. Zapier is the integration in this example, but you can create your own custom integration in the Hover dashboard (click here to learn more about creating those integrations).