These pictures won't work with the default skin when playing the full version of the game.
The pictures will show up on the team info screen, on the news screen, in the processing bar, on a match-day and in the stadium profile page.
The pack contains 4382 images of which the majority are 800x480px in size.
If you already have the FM19 pack with all three updates applied then you don't need to download the pack again just download the below update and move the contents into the pack.
Update 20.0 Download
If you already have the original FM20 pack released in November then you don't need to download the pack again just download the below update and move the contents into the pack.
Update 20.1 Download1/12/19 155 images taking the number of images in the pack up to 4382.
Extract downloaded file to a temporary folder.
In order to extract you will need either 7-Zip for Windows or The Unarchiver for Mac.
Move the folder to:
Documents\Sports Interactive\Football Manager 2020\graphics\
Create the folder "graphics" if it doesn't exist.
Run Football Manager 2020 and go to: Preferences > Interface
Hit the "Clear Cache" button at the top, and then hit the "Reload Skin" button at the bottom.