I just downloaded and tried to install the Episode 4 patch (from the final season.) and it's saying it's not the right version. I have the episode 3 patch applied.

I had the same thing happen. I fixed it by doing the following. I use the offline backup game installers and used this file (22 MB) to patch my episode 3 game:

Patch (152.8.102.123 (52:13) to 152.8.102.123 (53:13)) 152.8.102.123 (53:13) 22 MB

then I used the 1 MB file to patch it after the 22 MB file:

Patch (152.8.102.123 (53:13) to Episode 4 (152.102.123.34)) Episode 4 (152.102.123.34) 1 MB

and it upgraded to episode 4 for me.

You're welcome! :)