First get this copy of Zbrush https://piratebayproxy.live/torrent/11978463/ZBrush_4R7 and install/crack. 
Then open the main folder ZBrush folder C:Program Files (x86)PixologicZBrush 4R7 if you use default settings. 
Scroll down and you will see ZUpgrader. Run that and it should say there is an update follow the steps. 
Now when you launch ZBrush it will again ask you for a code. Do by phone enter request code click the button to get your activation key and enter it. 
Also before you download disable your AV or add an exception or the keygen will not load. 
I know it works cause I just did it this way and I am running ZBrush 4R7 P3 now which is the latest build. 
If any issues let me know and I will do my best to help