There are two places in-platform where you can access approved content.
Campaign Assets Tab
From the campaign home page, click on your in-progress campaign. From there, you'll see a list of tabs at the top of the screen, from Brief to Settings. Click on Assets to see all of the approved content from this campaign specifically.
Looking for all of your approved content, regardless of the campaign? Check out the Content Library, instead. Click here to learn more about the Content Library.