You need to download the Minecraft.dmg disk image, double-click it to mount it, then drag the Minecraft.app contained therein into your Finder -> Applications folder or use the shortcut window that pops up:

When I login on my sons side and try and double clicks on Minecraft in the Applications folder I get a pop up stating Unable to start Minecraft, if you are running from a dmg, please drag to Applications and try again. Oct 20, 2015 Minecraft updater Unable to start Minecraft, if you are running from a dmg, please drag to Applications and try again. It seems that this is related to permissions, because if I chown -R the app to the user who will run it, it works fine. You need to download the Minecraft.dmg disk image, double-click it to mount it, then drag the Minecraft.app contained therein into your Finder - Applications folder or use the shortcut window that pops up.

You cannot run the Minecraft.app while it is simply showing in the disk image, it must be dragged to the Applications folder so it can download/write the extra files it needs from the Internet. That is why you are getting this error:

Note: by and large, the only thing you'd ever need to be doing in the ~/Library/Application Support/minecraft folder is to delete that folder of your Minecraft ever gets corrupted. If you're having any problems, deleting that folder and run the Minecraft.app which you should have moved into your Finder / Applications folder. The support directory will be re-created from scratch automatically.

The information you're reading from that 2015 thread is very old and not an issue anymore.

Unable To Start Minecraft If You Are Running From A Dmg Please Drag

May 19, 2019 12:01 AM