You can set access rights for category and for the file.
 
Category Access Rights
 
In category you can set that files in the category can be downloaded by registered users only. But you can set that such files can be downloaded by only one selected user too. Specific user can be selected in Category Edit mode. Then all files from the category can be download by only selected user(s).
 
File Access Rights
 

You can allow downloading files only for registered users. Such files can be displayed for all users or only for registered users. If they will be displayed for all users, public users can see them but they cannot download them. Only registered users can download them.

Go to Components » Phoca Download » Files. Create new item or edit some existing item. Set Access level to e.g. Registered and set Display Unaccessible File to Yes. Now all users can see the file but only registered can download it.

The difference to Categories rights is, in Category you can select specific user, not only the whole group (registered, special).

 

Your Phoca Download component can be used for downloading files, which can be accessed only by selected users. The best way is to protect the category and set access rights for specific user(s). It is recommended to create a folder outside public_html folder on your server. There should be stored all protected files. In Phoca Download Settings you can set the path of this folder. Such files cannot be accessed by direct link.
 
 
Examples - Category Access Rights
 
Access Rights extends Access and if you set Access and extend it through the Access Rights (you will just specify one user from the group), the user must belong to such group. Otherwise he/she will be not able to access the files.

If Access Rights and Access are set, then two rules are checked when accessing files in category:

First - it is checked if the user is a part of the group
Second - if Access Rights is set, then the user is checked if he/she is selected in the Access Rights.

Access Rights just extend the Access and the user must be a part of the group.
 
Example: New ACL group is created in Joomla! and such will be set in Category in Access field.
 
Phoca Download Category Edit
 
 
 
Example 1:
Phoca Download - Example 1

I am not logged in: I cannot access the file
I am logged in as jan: I can access the file (jan is a part of registered and registered is group having viewing access for NewAccessLevel)
 
 
Example 2:
Phoca Download - Example 2
I am not logged in: I cannot access the file
I am logged in as jan: I cannot access the file ... because as jan I am not a part of the group Super Users
 
 
Example 3:
Phoca Download - Example 3

I am not logged in: I cannot access the file
I am logged in as jan: I can access the file because jan is in group NewAccessLevel (in this case only group is checked as the user is not set)