Hello,
I'm sorry but I'm not following you.
Guest users are stored in the HikaShop user database ; otherwise HikaShop won't be able to send them any kind of email notification.
And because it's a guest account, there is no Joomla account, so for sure, no password.
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.