Logic Pro 10.4.8 can't recognize HALion Sonic SE 3

iMac running on High Sierra. Have Logic running HSS3 with no issues.
Installing my software on an external SSD I have Logic, Dorico Pro 3 HSS3 sounds and HSS3 standalone version installed and running… BUT…
… LPX can’t find it! I have reinstalled and restarted my system but problem remains.

I realize I have to do this manually ( :confused: ) can anyone please tell me how?