Any luck bro??... I am also stuck at the same step.... for me also.... there is no option for AX7 CTP8 deployment... however i am able to download VM for CTP8 on local machine.
There is one more thing... while selecting environment i get 3 options...as u can see below. I cannot differentiate between 1st 2....also, both have different versions listed when i go to advanced options...
1st has: AX7CTP7.0.1186.16043
2nd has: AX7CTP7.0.1075.2399