I heard back from the person in the community who was having the same problem and he said that it just started working for him randomly. Sorry that's not terribly helpful -.-

Hello Yellowfish!

Do you have an anti-virus installed?

After a quick search, here are a couple articles that could help:
https://appuals.com/fix-steam-content-file-locked/
https://recroom.happyfox.com/kb/article/10-steam-corrupt-content-files-issue/

There is one other person in our community who was running into this issue too, so I'm checking with him to see what he did to get around it.

I will reply again when he gets back to me.

Sorry for the inconvenience!

Brett