Go to Tools, obs-ndi Settings, then put a checkmark in Program Output and name it whatever you want. Like I said, make sure you name it on the source PC.
I noticed OBS 28.1 has some different settings now when using NVENC by the way. It worked right from the get go but I haven't gone live with it, I only confirmed it worked perfectly when not streaming so far. Then you can change the settings to whatever you want. You need to name it on the source PC and then refresh the list on the 2nd pc and it will show up. I uninstalled the old stuff, updated OBS 27 to 28.1, installed this plugin, then when firing it up it said the NDI Runtime needed to be downloaded and installed, it grabs version 5 for you, installed it, fired up OBS 28.1 again and it's there. Click to expand.Yep, only you need to make sure your A/V doesn't instantly delete it.