Game Download:

Step 1: Install the Battle.NET launcher and create an account (if you don't have one already): https://download.battle.net/?product=bnetdesk
Step 2: Login to the BattleNET launcher and leave it open.
Step 3: Ensure you have at least 145GB of free space. Download this repository/releases/scripts.
Step 4: Right-click the batch file (.bat) and press edit to change the directory where you want the game installed. If you have a D drive with enough space, you can leave it as is. Then run the batch file, and it will begin downloading the game and show progress. You must not close the download box until it is fully completed. Once done, install the client.

Thanks to Watchful Wolf for the instructions.