Could you provide more details? Did you follow all these instructions?
server/BUILDING.md at master · CasparCG/server · GitHub
As stated in other posts on this forum from Julusian the server needs an X11 Display to get OpenGL information. Others have simulated this with sudo apt install xorg blackbox. I havent been able to make this work and am worried it will take unnecessary processing power to run this. Then I also fear it could be an issue if you are connected to the server via SSH when starting it. Then X11Forwarding and a bunch of other issues gets introduced.
From a post by Dimitry: CasparCG Server 2.1.12 NRK for Ubuntu 20.04 and 18.04 - General - CasparCG Community Forum (casparcgforum.org)
- For Ubuntu 20.04:
sudo apt install libtbb2 libglew2.1 libsfml-graphics2.5 libsfml-network2.5 libsfml-system2.5 libsfml-window2.5 libfreetype6 ffmpeg libfreeimage3 libopenal1
I have not tried the above method as of now. I will try it this evening. Have you gotten any closer since last posting?