Try this:
1. Download the SOURCE files from the original post
2. Download Mongoose 6.5 from here:
https://backend.cesanta.com/d.shtml?9DPNR5DTT1OX9RAD
3. Put the source files from the OP in a folder on your desktop
4. Extract Mongoose and put it in the SAME folder as step 3 above
5. Run MONGOOSE from the folder in STEP 3
6. It should launch a browser showing the INDEX.HTML of the payload on your PC
7. Go to your WiiU and ensure the DNS is set to AUTO ASSIGN
8. Launch the WIIU browser (delete save data) broswer will exit so launch it again (OPEN the curtains!!)
9. Go to address in WIIU browser as shown on your PC (type this EXACTLY including any HTTP and ports provided)
10. This will serve a white page with hyperlinks
11. Select EXPLOIT
12. With any luck about 5 seconds later you should see the WIIU logo in bottom right hand corner and it will launch HBL
let me know how you get on!