Hello,
First create your required user group (2 or more) in Users => Groups, and click on New to create one.
Give a name a parent group (registered if acces must be thanks to a login)
Repeat this to have several user groups
Second step, go in your categories configuration with
Extensions =>
HikaShop =>
Categories, select the categories you want to edit by clicking on the
little pen icon.
And in
Access level part, click on
Custom, and select your wanted
user group for this category.
With these configuration
Each user group can access
AND see only wanted categories
Hope this will help you.
Regards.