Step by step install on macOS

• double click the subtivals.dmg to make its content available (name will show up in the Finder sidebar), usually a window opens showing the content as well
• drag the application subtivals.app from the DMG window into /Applications (or on your desktop)
• wait for the copy process to finish

• eject the DMG (by clicking the eject button in the Sidebar)

• double-click subtivals.app icon from /Applications (or on your desktop)

• Click cancel

• go to system preferences on your mac, then "Security & Privacy"

• click "Open anyway"

• click the Open button. You should be up and running!

Happy subtitling !