I've just downloaded a fresh copy of 1.22.x and entered the 1.21 key -- works perfectly fine. And as
ubermaan already pointed out, your
screenshot clearly shows why you couldn't add a key to your previous installation: "Access to the path 'Keys/1.21' is denied".
Here's a quote from MeshedVR on "How to install VaM":
IMPORTANT: choose a folder that is not admin-rights protected. For example, don't try to install to Program Files directory as that is admin-protected. VaM needs to be able to write files to the directory you install it in.
You failed to do so, and that's why they key didn't seem to work.