how to record stereo

I am so puzzles here guys. I have a Focusrite 18i20 and Reaper. I need to record a stereo output from a E Drum. So I have a 1/4 stereo cable from the module. If I plug this in to channel 1, on my Focusrite. I can only select Stereo 1 and 2 for input. But I am only passing signal into channel 1. How in the world do I do this? Thank you for your time

there is no way of plugging a stereo source into a mono input & retaining a stereo signal, you'll have to use two channels

Probably going to have to do a splitter, unless your module has two TRS Outputs. My Roland SPD-SX does, as well as most Roland V-Drum modules to my knowledge. Maybe post the model of the drum module so we can look it up and see what sort of Outputs you're working with (or just take a picture or list them).

Thank you everyone for the fast response and help. I was really hope for some way to do so. I will just use 2 channels. Thank you guys