Looks like a Mac operating system security measure of some kind..
Does this happen when you open After Effects in particular? Any more contextual information you can give?
Mac OS asks me to authorize the file when putting it into the plugins folder, then, when you open AE and drag the plugin onto a layer, it says it’s unable to authenticate
This sounds like a security measure similar to the Windows UAC system of some sort that Mac OSX has.
Maybe check some of the security settings mentioned here? There seem to be other softwares that have this issue as well.
