Connect Audio Mixer to Laptop

[Colonelperson]

I am working with my school's audio system. It is already set up to input two mics into an ASHLY analog mixer (rack mounted), send 1 TRS output directly to some speakers, and the other to a Bose amplifier, which outputs to other speakers. I am trying to connect my laptop to the system as a second output so that I can livestream from OBS. The problem is that the neither remaining outputs (line out rcs or xlr output) will register as an input on my computer, only an output. I have been testing with two different laptops, both of which have audio input through the headphone jack, however, the actual laptop I will be using is an Acer Predator Helios 300 (12th gen CPU, RTX 3060). I was hoping to get a more definitive answer here than Google, since I have seen five or six different answers that I know don't work.