I ran into the same issue. It downloads a .rar file, not an apk file. We have to find a way to extract it before we can potentially install it.
if you figure it out mind letting me know
not sure if this works on android but have you tried winrar
You can always use winrar on pc and simply move the file to your android device. Or you can use the tool I mentioned below.
There's a guide to install Android Version in our discord <3
you can use one of the many .Rar apps that exist, I'm using one just called RAR (all caps, by RarLabs) on my tablet. It's a little bit of a mess to update the game, but it's very doable!
Try changing the extension from .rar to .apk
