it turned out, that issues happened with LibreCAD-2.2.0-rc3.dmg on Big Sur. Presumably it is not related with M1 CPU.
Anyhow, I assume that your M1 Mac has Big Sur and thus you need LibreCAD-2.2.0-rc3-BigSur.dmg.
With automatic builds coming soon this should be solved and we can return back to one package for all MacOS in future.
investing less than half an hour into Search function can save hours or days of waiting for a solution