In a few quick steps you can have a page listing all of your collections, or brands!
The first step will be getting into the theme editor, 'Sales Channels' > 'Online Store' > 'Themes' and then to the 'Actions' icon to 'Edit HTML/CSS'. From here the 'Add a new template' option can be used to add a new page. In this case we can just call it 'directory'. The name doesn't have to be anything in particular, it simply makes it easier to remember when it's time to use it.
After your page has been generated you'll see some default content there, that can be deleted. In place of that content, the following code can be copied and pasted in.
For a directory of all of your collections:
For a directory of all of your brands:
After your new page has been saved, in the 'Pages' section of your admin you can create a new page and choose your 'page.directory.liquid' template from the dropdown. That's all there is to it!