Hello,
It's no related to HikaShop at all.
By activating the plugin you ensure that Acymailing is used during HikaShop triggers.
Like "onAfterUserCreate" trigger which will load Acymailing core.
But HikaShop do not send emails ; it uses the Joomla core for the emails but Acymailing can override Joomla mail.
That override is only related to Acymailing and there is nothing (nothing at all) in HikaShop to configure "smtp" because HikaShop do not handle emails at all !
So I'm really sorry for the Acyba team but we have nothing to do for their issue.
They have to handle it.
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.