Here's how I got mine:
1. Get a VPN that can connect to Indonesia and connect your VPN to an Indonesian server.
2. Go to the Steam website (NOT APP. Make sure to use a search engine to find the Indonesian Steam and then translate the page.) and create an Indonesian account. Very important that you do this on the Indonesian site
3. Add game to cart (should be 375,000 RP)
4. Go to seagm.com and get an Indonesia Steam card. (400,000 RP cost $25)
5. Add steam card to account.
6. Check out. Then log in on the Steam app with the account and download. You can use this account alongside your current US account (or whatever country your current account is)