If you can’t compress a file or folder on Mac
If you can’t compress your files and folders, check the permissions settings for those items. If permissions aren’t correct, you might not be able to copy, move, or overwrite certain items.
On your Mac, select the item, then choose File > Get Info, or press Command-I.
Click the triangle next to Sharing & Permissions to expand the section.
Click the pop-up menu next to your user name to see the permissions settings.
If you’re not logged in as an administrator, you may need to click the lock icon and enter an administrator name and password.
Change the permissions to either Read & Write or “Read only.”
If you can’t change the permissions, contact an administrator of your Mac or the owner of the file or folder.