i think bitcoin market admin should fixed this issue, i got mad and confused as well, because i entered and double checked by email before placing the order.
waited 24 hours nothing in the inbox, then emailed the support.
they told me to check spam or junk folder, and the private key was there.
thank you again bitcoin market for running a legit service, in the midst of 100,000 scams on deepweb by lowlife scums.