Entity browser or Media Library for PDF uploads?
Going to Home &gt;&gt; Administration &gt;&gt; Configuration &gt;&gt; Content authoring &gt;&gt; Entity Browsers and creating a new entity browser is the right way actually.
But you probably have attached a media entity field to your content type therefore you must configure your new entity browser to be used on the media form display level.
Lets say your new entity browser is called Document browser you should go to the media form display for document media and make use of the new entity browser.
Here is a screenshot that might help understand better

The content type form display widget for the respective field should remain as Media library in order to pick up the media library from previous step.