First, select the game that you want to download, and select the download prefix. For pico-8, it's "7tiann/pico-8". For picotron, it's "8pwrtp/picotron". Voxatron is "5r8npa/voxatron".

Next, select the OS. For macosx, it's "osx", for windows, it's "windows", for 32-bit Linux, it's "i386", for 64-bit Linux, it's "amd64", and for raspi, it's "raspi".

Now, fill in the blanks in this URL. "https://lexaloffle.com/dl/{download prefix}_{version without the v prefix}_{os}.zip". Just navigate to that URL, and it should download, unless you malformed it or tried to get Picotron for Raspbian. (It's not released yet. I don't know what you expect.)
You can get the current version from Lexaloffle's website.

I'm a bad writer.