Saving Excel files on Mac

1. Check the file format: Make sure the file format is supported by Excel (e.g. .xlsx, .xls, .csv, etc.).
If the file format is not supported, try converting it to a supported format.
2. Check file permissions: Make sure you have write permissions to the target folder.
Right-click on the target folder, select “Show Profile”, and check the “Sharing and Permissions” settings. 
3. Check storage space: Open “About this computer” > “Storage” to check if there is enough space on your hard disk.
If there is not enough space, delete unnecessary files or applications to free up space. 
4. Use “Save As” function: Open Excel, click “File” > “Save As”.
Select the destination folder, enter the file name and click “Save”. 
5. Check for Excel updates: Open Excel and click “Help” > “Check for Updates”.
Make sure Excel has been updated to the latest version.
6. Reset Excel Preferences: Close Excel.
Open Finder and navigate to ~/Library/Containers/com.microsoft.Excel/Data/Library/Preferences/.
Locate and delete the following files:
com.microsoft.Excel.plist
com.microsoft.office.plist
Restart Excel and the system will automatically generate a new preferences file.
7. Contact Microsoft Support: If none of the above methods work, it is recommended to contact Microsoft Support team with detailed error messages and screenshots for further assistance.