So you installed a new module to your OpenCart store, but you see Permission Denied error and cannot access it’s administration page. If you have no idea how to fix it, here’s a short tutorial how to do it.
OpenCart user permissions – why they are used for
OpenCart administration panel can be operated by more than one user account. For example, you could have product editors in your staff that add or edit product information, store administrators that setup new payments, shipping modules, and so on. You obviously don’t want your store editors to mess with main store settings, so you can create different user groups that can access different parts of your OpenCart store administration pages. Then you can select user group for every user in your store.

User admin panel can be found at Admin Menu >> System >> Users >> Users. Here you can add new users and edit user information (and set user group).
User groups can be added or edited at Admin Menu >> System >> Users >> User Groups.
How to fix the user permissions issue in OpenCart
If you just installed new OpenCart module and you’re getting Permission Denied error, it means that your User Group does not have rights to view or edit the module. What you need to do is go to Admin Menu >> System >> Users >> User Groups page, select your user group from the list, and hit Edit button. Then select your module both in Access Permission box, and in Modify Permission box. Hit Save button.

That’s it – you are now allowed to view or modify the module you just installed.