Hello,
With HikaMarket, your vendor can configure (and upload) product files directly from the front-end.
Some files can be "private" (only available when you buy the product), other can be "free".
For the rest, it's purely HikaShop related and I know that there are some thread in the HikaShop forum which are talking about that kind of usage.
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.