Hello @longyup, for the first half, SDL not found looks like the more important detail there. I think you've encountered the CentOS equivalent of #7036. Looking around I'm not seeing a readily available 32 bit SDL2 system package, so you'll most likely need to look into running SteamCMD in a steam-runtime environment or something that can provide an equivalent set of libraries.
For the second half, you may get better feedback in the Servers section of the game's Steam community forums.
This is an error caused by the absence of the 32-bit SDL library.
sudo apt install libsdl2-2.0-0:i386
solves the problem.
Nothing extracted yet.
CentOS Linux release 7.8.2003 (Core)
I use steamcmd, and see 'Steam>Warning: failed to init SDL thread priority manager: SDL not found'
and i run 7daysToDieServer
[S_API FAIL] SteamAPI_Init() failed; SteamAPI_IsSteamRunning() failed.
and server not been run