Open Studio > VST Plug-in Manager in Cubase 10. Does EZdrummer 3 show up in the blocklist?
Are other VST 3 plug-ins being detected under VST Instruments? Try clicking the update/rescan button in the top right of the Plug-in manager window. Does Cubase find EZdrummer 3 then?
There should be a EZdrummer 3.vst3 file in Macintosh HD > Library > Audio > Plug-Ins > VST3. Is that file there in Finder?