If you are using Studio Pro this document gives you a step-by-step guide on how to download and install content from the Mendix Marketplace. It should be what you need.
Hope this helps
You can also click on cart sign next to profile icon shown in below image and it will directly redirect you to the marketplace, you can search your module/widget and directly download it in your project.
Step 1 :- Go to mendix market place
Step 2:- On Left Navigation there’s Content Type, where you can filter based on category and download it
Refer the image below.