Then you could download the game via vpn, log out of steam, disable VPN, go to your main and add steam unknown game and select the Ravager.exe file. I think this shouldn't violate anything.
Hope this works for you mate.
It should work though. I did it just 5 minutes before writing the comment.
Maybe you need a vpn? This is the only thing i additonally had when i bought this game and activated sharing with my main account. Are you sure you cant buy like a 15$ Giftcard or any equivalant amount from a third party website?
Edit: Yes you actually need a VPN to play this Game. It only needs to be on until you started steam and logged in, after that you can disable it again and it will show the game in your library. Feel free to tell me if it worked or not.