Hi,
Unfortunately, with the information you gave us ; we can't be more specific.
Like I wrote you have to customize the email and that customization requires some PHP knowledge.
All the user data is available thanks to the " $data " variable object, in that object you should find the custom field value.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.