These will not work on the default skins, a custom skin needs to be used.
I highly recommend FLUT Skin.
The pack includes over 9,700 stadiums from over 50 countries and over 100 divisions around the world.
The pack currently has the same files as the one for FM20.
How to add Mini Stadiums on Football Manager 2021
- Download the .rar archive and use a tool such as 7-zip for Windows or The Unarchiver for MacOSX to extract its contents.
- Move the extracted contents to your graphics folder:
\Documents\Sports Interactive\Football Manager 2021\graphics\
Create the folder "graphics" if it doesn't exist already.
- Run Football Manager 2021 and go to Preferences > Interface:
Hit the Clear Cache button. Return to this screen.
Enable Reload Skin when confirming changes in preferences
Hit the Confirm button