Hey there!
First, I want to give credit to the two original replies, who 100% solved this problem for me. You guys are the real MVP's and really saved me today.
Second, looking into both options presented, I found my own solution which I hope will be easier for the average person looking to install Windows 10 on a Mac.
When the computer boots into Windows the first time, the Boot Camp menu automatically pops up.
1. QUIT THE BOOT CAMP INSTALLER. Don't even start it.
2. In the WININSTALL drive, click the folder that says "Bootcamp"
3. Click "Drivers"
4. Click "Realtek"
5. Install the Realtek Driver.
6. Once this finishes, drag the Realtek Driver to the Recycle Bin. THIS IS THE MOST IMPORTANT STEP
7. Restart your machine.
8. After your computer starts up, click the WININSTALL drive again.
9. Click the "BootCamp" drive again
10. Click the "Setup" file
Run the setup as usual, it will complete without issue.
Basically the only thing i'm doing here is installing the Realtek driver manually, and then deleting it from the Setup package so there is no issue in the first place. This hopefully will be easier than using task manager to quit a part of the setup process manually, OR having to rename .exe files to help the install. Good luck, and PM me for any and all questions!