The easiest way to sync with the SK400 II and have the most control would be to get a for-Canon Godox 2.4 GHz radio transmitter unit for your camera hotshoe: e.g., an XPro-C or Flashpoint R2 Pro II-C, or TT685-C. The SK400 II has a built-in radio receiver in the Godox system, so a Godox transmitter on your camera could remotely fire, adjust the power, and control the modeling light on the strobe.

Using a TTL sync cable is not possible, since the SK400 II does not have a flash foot to attach it to. Any other sync cable would require a 3.5mm connector for the SK400 II, and a PC (Prontor-Compur) or 3.5mm connector and a hotshoe-to-PC (or 3.5mm) adapter for the M50, since it does not have a flash sync port of any kind built in. And a PC/3.5mm sync cable would be a manual-only connection that could only allow the camera to fire the strobe. All other settings would have to be adjusted on the strobe itself.

You could, however, also use the pop-up flash on the M50 to remotely fire the SK400 II, since it also has the S1/S2 optical slave modes. If your pop-up flash is in M, use S1; if your pop-up is in TTL, use S2, so that the metering pre-flash is skipped and won't trip the strobe too early. This is also manual-only but wouldn't require you to purchase any additional gear.