I'm sorry, could you explain a little more so I can help you figure out why it isn't working?
Did you have Ch4P1 already installed? or Was there a particular error that occurred?
Any more information might help me solve the problem for you.
This update is a little different from previous ones as it's just a patch. I go into more detail here as well as provide simple install instructions for the update.
https://jabbonk.itch.io/homelander/devlog/772010/chapter-4-part-2-update-patch