Okay lets get the simple things out of the way.
Make sure you have compatible system firmware, make sure you are scanning the right web site.
Your first mistake: is you have the wrong amount. Nothing in the first slot and 13,000 in the second slot is for the 6th villager not the 4th.
Unless you mean you want to move PLAYER 4s house (File Number 4). Then thats an entirely different value. File 4 is 0 in first slot and 3,000 in the second.
Next, go to the browser and clear your history and cookies. DONT RUN THE TOOL YET! After you clear history, press home, then just go back to the browser and run the tool/scan qr code.
Thanks for pointing out my mistake about the bell amount! However at the time I had 7 villagers so the sixth villager house should have moved but when I tried the tool the sixth villager's house was in the same spot it was originally was and the 100 bells was still where I placed it. I am on 9.4. I don't understand why the building seeder doesn't work, everything but that seems to work fine. I tried clearing cookies and history but that didn't help. I used the qr code from imgur and the one provided on gbatemp.