Prowlarr is not compatible with OSX versions < 10.15 (Catalina) due to .NET incompatibilities.
codesign --force --deep -s - /Applications/Prowlarr.app && xattr -rd com.apple.quarantine /Applications/Prowlarr.appopen /Applications/Prowlarr.appDue to Apple Security Restrictions, the Application's Updater must be self-signed as well or you must manually install updates. This is primarily due to the Personal Information required by Apple to sign applications.