I do not encourage piracy. Please make sure you own the original game. Thanks to the Game Restorers for their excellent texture pack! I have added a few tweaks to fix some issues.
Join their Discord Server here!
From the dropdown menu, click on the Google Drive Link. You'll be guided to the Game Restorers page. Click on Download. Once it is downloaded, unzip the folder and place the RSP folder into your Dolphin texture folder. To find it go to your computer's Documents folder then go to the Dolphin Emulator folder and then the Load folder. Here you will find it.
For macOS, it should be in the Application Support folder.
Enabling the Texture Pack:
Now open Dolphin and go to the Graphic options, then select advanced. Now open up the game!