I'm trying to open a download and I keep getting this message: TurboTax can't be updated when it's running from a read-only volume like a disk image or an optical drive.

Please see this Turbo Tax FAQ for assistance with the error.

Troubleshoot TurboTax for Windows updating issues

Me too , running Mac Big Sur.   Can't find anything on this site that helps.   

@bobtidmore 

This old thread was about a WIN issue ... 

TurboTax minimum system requirements for Mac - https://ttlc.intuit.com/community/system-requirements/help/minimum-system-requirements-for-turbotax-...

Find download using Mac - https://ttlc.intuit.com/community/installing/help/find-your-turbotax-for-mac-software-download/01/25...

Install TurboTax for Mac - https://ttlc.intuit.com/community/installing/help/how-do-i-install-the-turbotax-software-for-mac/01/...

Troubleshoot install for Mac - https://ttlc.intuit.com/community/installing/help/turbotax-for-the-mac-installation-troubleshooter/0...