There are several factors that can cause a Sync Agent to not respond when trying to configure it.
When you install a Sync Agent you want to download it from either Password Server > Sync Agents Actions - Download Agent Installer or C:\Program Files\Scorpion Software\AuthAnvil Password Server\AAPS\SyncAgent Setup\SyncAgent Setup Package.zip.
Note: You also want to ensure that you are installing the Sync Agent from the local hard drive of the server. Installation from a Network Share will cause errors.
Ensure that the Server with the Sync agent can resolve http(s)://FQDN/AAPS/AAPS.svc