When defining a connection it is recommended to test it to assure it is working. This is done by selecting the connection and clicking the Run button. If it fails, look at the Results tab for detailed error messages.
Some connectors like the User App connector, require the SSL certificate to be in the Identity Validator 2.0 truststore file. By testing the connection to the User App server, it auto-imports the certificate thus allowing the connector to connect via ssl (https).