Read "How to open an app from a unidentified developer and exempt it from Gatekeeper" in OS X: About Gatekeeper - Apple Support.
I just purchased a Mac running the latest high Sierra. I downloaded presets from Jake Olsen studios to use in Photoshop but when I try to unzip the file I get a message stating that I cannot unzip them because it only excepts installations from the App Store
Question marked as
Best reply
Read "How to open an app from a unidentified developer and exempt it from Gatekeeper" in OS X: About Gatekeeper - Apple Support.
2 replies
Question marked as
Best reply
Open System Preferences > Security & Privacy > General
click the padlock, enter your password then click "App store and Identified…"
how to install a zip file containing photoshop presets