A specific DLL is required for integrating Metadefender Endpoint for Guest Devices with Juniper Host Checker as a third party policy.
Contact support for a copy of the DLL, and follow the instructions (method #3) in the Metadefender Endpoint | Juniper secure access integration guide.
The guide is attached with this KB. (The documents refer to Metadefender Endpoint which is formerly Gears Client)
To contact support: http://www2.opswat.com/about/contact-us