1| You will first need to enable the Anti-Virus blade on the Security Gateway object - General Properties topic. Either enable each specific blade or Autonomous Threat Prevention.
2| Then go to - Security Policies > Threat Prevention > Custom Policy Tools > Profiles. Check the profile you would like to use and check the relevant settings for Archive scanning
Make sure the Threat Prevention Profile is used in Threat Prevention Policy
3| To use HTTPS Inspection enable it on the Security Gateway object (HTTPS Inspection topic)