Mario Maker wants the 1.01 launch update, thats the error you get when launching the game with the Spoof'd 5.5 Firmware.
Its ok to have Nintendo URLS blocked via router or whatever.
Download NUSGrabber and NUSGrabberGUIv1.6Update1 (this one has a simple to use interface with a drop down game selection)
Launch NUSGrabberGUIv1.6Update1 and wait for it to load titles.
Click game update and find the mario maker game in the drop down, make sure u select your region
Click download, takes about 5-10min to download all files.
They will be saved in the same folder as NusGrabber, it will be called 0005000E1018DC00
Once down downloading, select all files inside the 0005000E1018DC00 folder and place them in your SD card inside your install folder, only contevts of 0005000E1018DC00 belong inside the install folder on the SD card.
insert card in wiiU, power wiiU on.
launch browser and refollow steps you took for the Spoofer, only now wait 20-25mins for the files to install blindly.
Reboot WiiU and play your updated mario maker game