HELP: Can't Get Live Video

I've been put in charge of a live stream event in a couple of weeks, and am testing things out now, so as to not have issues when the time comes. After talking with someone else I know that does events professionally, he gave me a list of products to get.

Here is my setup:

• Vivitar 4K Camcorder (consumer grade)
• Blackmagic HDMI to SDI Converter
• Blackmagic Decklink Duo 2 inside of a Sonnettech Echo Express SE I PCI Enclosure
• Acer Nitro Laptop
• OBS Studio

The issue I'm running into is that I can't seem to the camera video on the laptop. The only way so far I've been able to do that is by connecting a USB directly from the camera to the laptop. If I use the HDMI out of the camera, I can get a static image in Blackmagic Media Express, but that's it. I do not get a live preview. When I open OBS Studio, I get just a black screen no matter which video input I select or which settings I use. This is very frustrating.

Thanks

I would think your friend who recommended what to purchase would be the best person to ask...

Have you tested using a different HDMI source? If USB works, why not just use that?