It’s true. Audacity only supports one channel of sound. Many multi-channel devices (beyond stereo) configure their sound as blocks of stereo. Audacity sees each block as one channel. I think there’s a trick to getting 3 and 4, but you would only have 3 and 4. It drops 1 and 2.
Does support mention “ASIO” anywhere? Typically, ASIO is the interface software that allows you to “see” all four channels at the same time. Audacity doesn’t directly support ASIO, although you can build the Audacity program yourself with ASIO support. Ever build a program?
There is a forum section devoted to multi-channel.
https://forum.audacityteam.org/t/multi-channel-recording-in-audacity/15644/1
Koz