Thanx for your help. Palemoon 20.1, yes I “zipped” all mentioned files and folders in one compressed file, using WinRAR 4.20. Then I changed extention to .xpi, did every needed settings in Avast WebRep & Antiphishing and dragged .xpi to open Palemoon.

Result is always the same :Instead of usual Palemoon installation window this error sign pope up…“This Add-on could not be installed because it appears to be corrupt.”

Any idea? Thanx again for any help.