C++ how to connecte many player with one client

Hello,
I have some questions because I am in doubt even with the documentation of TS3sdk client.
I have a TeamSpeak sdk c++ server and I have a client (it’s a game server) that initializes teamspeak : (in constructor)
ts3client_initClientLib and ts3client_getClientLibVersion

But it is also this client that connects the players to the teamspeak server channel (c++)
On this same server when a player connects I do this :
(in login function)
ts3client_spawnNewServerConnectionHandler, ts3client_createIdentity, ts3client_startConnectionWithChannelID, ts3client_freeMemory(identity), ts3client_getClientID

but ts3client_getClientID is always initialized to 0 which I find strange.
That’s why I was wondering if I should initialize only once ts3client_spawnNewServerConnectionHandler for all my players who login to the channel?

I tried to do it only once, but as soon as a second player logs in, my server crashes error connection.

Can you tell me more about initializing a player connection?
My player connects directly via the game server and not an external teamspeak client.

thanks in advance