What about UNSUPPORTED required packages and WHERE is SocketAsyncEventArgs defined?

Hi, all.
I'm searching information about async socket connections and I found this example but I've trouble while using it in vs2022 community.

1) Adding REQUIRED reference "System.Net.Sockets.dll" nuget manager doesn't shows download option so I changed it in "runtime.win.System.Net.Sockets"
**Is it is correct?**

2) I get error "SocketAsyncEventArgsPool not found...".
MSDN says that is in System.Net.Sockets.dll but I removed it due to previous point.
**So, WHERE IS SocketAsyncEventArgsPool?**

3) I get error "CS0144 Cannot create an instance of the abstract type or interface 'BufferManager' " on this line:

m_bufferManager = new BufferManager(receiveBufferSize * numConnections * opsToPreAlloc...

Please, let me understand. :-)

Thanks in advance for any answer.

AS