We have some great help content (articles and videos) which will run through how to build category and subcategory menus using content templates. 

1. Create an "All Products" Parent Category (this would essentially just be a name for a regular category).

2. Go to the Display Settings tab and tick "show category navigation" in this and all child categories you create under this parent. (The hint explains: enabled this to show the category navigation side menu for this category. Please switch the page to a 1 column layout if you're using 2 column layout).  
 

When this is enabled, the user will see all categories they have access to on the left hand side of the page.  
 

 
3. If you wanted to fill the empty space on the right hand side of the page (the all products category with with categories based on their access permissions, then you can link the categories to the "all products" category using the Parent Category option within the category like so: