Mixer help

The only configuration you can do with this mixer is one mic (or mono line-level signal) each on Channel 1 and 2; and the combined channel 3 & 4 input is good only for a stereo source, such as your Zara connection.

The USB socket is not a bidirectional bus to connect to a computer, but appears to be an internal player input that receives a thumbdrive with MP3 music or other audio on it. Notice the transport buttons next to the socket, intended to play and skip audio files.

Assuming you won't be transmitting a stereo signal, and that all your sources are mono (or can be properly summed to mono as explained in the next paragraph), you can do a single host mic in Channel 1 with an XLR cable, a CD player mono input into the Line socket of Channel 2, and your Zara computer into inputs 3&4, presumably using a stereo 1/8" to RCA cable, depending on your computer soundcard. You can put some music and station imaging on a thumbdrive and play them with the internal MP3 player, but that means having to switch Channel 3&4 back and forth with the MP3/ST button as you need to. Not an elegant solution.

I dont know what kind of input jack is on the Talking House transmitter, but you will be plugging 1/4" cables into the MAIN sockets and summing the channels to mono.  To do this, you CANNOT be using a "Y" cable or adapter, but a summing circuit. The RANE company tells you why in this informative webpage:  https://www.rane.com/note109.html    and the same applies to the mono output from the CD player I suggested.

I get that we all can only have the gear we are able to comfortably afford, but I would have held out for a six- or eight-channel mixer in this case, Rock. Then again, we've all made-do along the way with less resources than we wanted, so let me wish you luck for a successful outcome.