Hello,
Please make sure that you have both Read and Write privileges on the /Documents/Eventide folder, as well as the /Users/Music folder, and then run the installer. This article can help you with that: https://support.apple.com/guide/mac-help/change-permissions-for-files-folders-or-disks-mchlp1203/mac
If you are still getting the error, try manually copying the contents of Documents/Eventide to Music/Eventide, and then running the installer.
If neither of those work, please see a few posts down where another user found their own solution you can try.
