It never fails that enterprise IT allows you to run homebrew, but doesn’t give you privileges to write some of the typical directories homebrew uses.
When brew install ...
fails, you can use a workaround by installing in the user ~/Applications
folder.
It also never fails that I forget the exact syntax for that.
It’s simple.
Run
brew install --cask slack --appdir=~/Applications
to install Slack (or whatever you need to install).
Note
This only works when there’s a cask available for the package.