i read through all of the steps in the FAQ section, and i've done it, but every time i put it in the fonts folder or press install, a message pops up saying "... is an invalid font."

I'll bet you're trying to install the .zip file, rather than extracting the .ttf file from the .zip, before installing the .ttf.

First, extract the TTF or OTF files from the Zip file. Not only open the Zip file but save the TTF or OTF in a folder of your disk.

Second, you install it.

achase23 probably has that o so handy Windows feature 'Hide extensions for known file types' active. So he/she doesn't see that it is a zip and not a ttf/otf.

So, first of the first, active the Windows option "show the file extensions".