I don't currently have enough on-site reputation to post a new answer to permission error when installing ttf-mscorefonts-installer, but due to the up-votes on my comment under https://askubuntu.com/a/812152/269638, I presume that my comment has helped a few users with this (or related) error.
Shall I edit the answer I commented under? Can my account be unlocked to make a new answer (as I'm under the au.se reputation limit that excludes the association bonus)? Is there a way to answer in the form of a "community wiki"? Or should I just leave it as a comment?