Hello,
HikaMarket is an add-on for HikaShop ; that point is very clear in the website, product page and also in our communication.
HikaShop is the e-commerce system and do provide its features.
HikaMarket adds features regarding the front-end edition of the store and the marketplace/multi-vendor features.
But because HikaMarket is an add-on, it do not include features that are already in commercial edition of HikaShop.
The problem related to the creation of vendor custom fields in HikaShop starter will be fix in the next release.
Afterwards, the system allows you to use all available type of fields ; which also include the plugin fields (like the advanced date picker or others).
I am sorry that the "files" fields are not available in the starter edition and I don't know right now if it's something which would change in the future. HikaShop is made by one team and HikaMarket is made by me.
Via commercial edition of HikaShop you will have access to the specific features (which are describe in the HikaShop compare page), including "product / category / order / items" product fields and much more.
www.hikashop.com/extensions.html
If you don't want to use a commercial edition of HikaShop ; it is still possible to use custom plugin to extend the custom field types ; or use another type of field for the customization of the vendor page by your vendors.
Personally, I do think that you might need features such as product custom field (essential and business) or order custom fields (business), features that you can find in the commercial editions.
HikaMarket is complex, it needs to have a high level of security and provide a lot of front-end (flexible) interfaces to provide to the vendor a full system for the store management.
Regards,