For Single Users
1. Edit Categories
ACP -> Categories -> Edit Categories -> Categorie -> Edit -> Upload -> Private
2. Edit User
ACP -> Users -> Edit Users -> User -> User Permission -> Categorie Upload -> Yes
or
For Usergoups
1. Edit categories
ACP -> Categories -> Edit Categories -> Categorie -> Edit -> Upload -> Private
2. Add Usergoup
APC -> User Groups -> Add User Group (Upload) -> User Goup Permission - > Categorie Upload -> Yes
3. Edit User
APC -> Edit Users -> User -> User Groups -> User Group Upload -> Yes