Etcher using Mac High Sierra is not working

am new to this. Tried to use Etcher to burn iso to FAT32 USB stick, but only files Mac would activate the Open button, Etcher wouldn’t accept as burnable image. Gave it up. Too bad, 'cause I have full set of Raspb 4 with keyboard & display. Sorry this don’t fly yet.

Hey there @gerik welcome to the forums. Could you confirm what version of macOS you’re using (the version number from ‘About This Mac’ and also what version of Etcher you’re using? It may also help us to reproduce if you share what .iso file you’re trying to flash also, we can then try to reproduce it on our side.