To do Alt + A R C on Mac in Excel, download and install Accelerator Keys, then press Option, followed by A, R, C.
Command: Cancel Refresh
This is how to do Alt + A R C on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + A R C cancels any currently running data refresh operations. This is useful when a refresh is taking too long or you need to stop it to make changes to your queries or data connections.