Here is How
All you have to do is go ahead and install Resident Evil 7 / Biohazard 7 Teaser: Beginning Hour, which is basically the demo that came out before the main game. After you do that you should follow this guide on how to get that pesky little coin.
The Fastest Way to 100% Get the Dirty Coin
If you did everything right, before you launch a new game of Resident Evil 7 the following message appears: "Item obtained in demo has been added to the Item Box in the main game."
Written by Condestavel.