Troubleshooting Micro Converter BiDirectional SDI/HDMI 3G (t

I recently got this converter assuming I could use it to get a signal from either my Macbook Air M1 or iPad Pro onto an older CRT (Sony Trinitron - I do lots of bouncing between digital and analog stuff in my work).

Current flow I've tested is: Macbook Air and/or iPad out to HDMI > Black Magic Micro Convertor > SDI out into a BNC-to-RCA adaptor > in to my CRT. This doesn't seem to work.

My cheap Amazon conversion box seems to work with the exact same cables/flow, and I was hoping that this would be a better quality/more reliable option. Am I missing something?

Thanks for any ideas

That old Sony probably has an analog input (composite), while SDI stands for serial digital interface.
The converter is strictly digital. Even if the connectors look the same, the signal is not.

You would need an additional converter
Mini Converter SDI to Analog

That will take the SDI signal from the Micro Converter and convert it to analog.