I started a new topic for you. It is too hard to deal with multiple people in the same topic on different systems and using different versions of Audacity.
Try Installation: Do NOT run Audacity from the DMG!!!.
Then try changing the project save directory to your own Music folder. It should not be necessary to avoid a folder that is open in other applications, but you can investigate that. Is that a known issue with Word, cyrano?
There are two restrictions when typing the file name for the saved project. Don’t use colon, because the Mac reserves that character. Don’t use backslash ( \ ) due to an Audacity bug.
Gale