1. Download
http://www.mediafire.com/file/kdq6dz...adium.zip/file
2. Unzip and place here:
[PC] Documents ▸ Sports Interactive ▸ Football Manager 2020 ▸ graphics ▸ backgrounds ▸ stadium
[MAC] Users ▸ YOURNAME ▸Library ▸ Application Support ▸ Sports Interactive ▸ Football Manager 2020 ▸ graphics ▸ backgrounds ▸ stadium
3. Go to preferences (advanced and select interface) and ensure "Reload Skin" is ticked (you may need to clear your cache too) and click "confirm". As per the below screenshot.