Hi,
The HikaMarket registration form required an HikaShop user (so a Joomla user). If the user is not logged, you will be redirected to the login screen.
HikaMarket does not create users at all ; Are you sure that you validated the right form ?
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.