Hello,
Regarding the front-end and email links, please open a new thread in the HikaShop section of the forum.
For the HikaSerial part, you have your "virtual file" and when you have access to the link, you can download the image generated by the plugin.
The issue you're describing is related to the HIkaShop frontend and how downloadable links are displayed.
The HikaShop team will need to check your HikaShop version number and your overrides. (for the front-end order and the mail overrides)
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.