Hi @Eric Hanson ,
Thank you for your question. Some cameras are compatible with external stereo microphones and others are not. When viewing the Canon EOS M50 Product Manual, there is no information regarding what type of microphone is compatible, whether the external mic input supports stereo audio, or even if the camera contains a pre-amp...at least that we could find. You can find the product manual here. Have you reached out to Canon support team for assistance?
The Blue Yeti has its own headphone amplifier for direct monitoring, which is why it most likely works with the camera. This output is a line level output and doesn't require a preamp, because it's built into it. The 3Dio output is a mic level output so you can use your own preamp without compromising quality.
If you intend to record directly into your computer, we recommend the Focusrite Scarlett 2i2 as a stereo audio interface. This device contains both a preamp to boost the signal to line level as well as an A/D converter so you can record digital audio directly to your hard drive.
Another option, is the Zoom H1n. It is a small, stereo digital recorder that you can use to record onto a micro SD card or you can use it as an audio interface connected to your compauter as well. It is portable and light weight and provides really great quality and convenience for the price.
I hope this information helps. Let us know if you have any other questions.
3Dio Customer Care