I recommend you search these forum for USB hub overload/monitoring tool to make sure all of you USB devices aren't on same USB controller, and that causing problems.
There are lots of YouTube videos and guides (on here, I think) that walk thru the basic settings for OBS to use with 720p stream to Facebook. [sorry, I'm not at my computer to post references to ones I found most helpful]. For real basics, I'd recommend looking up on YouTube OBS FB live stream tutorials aimed at churches... because they expect less technical users.. so real simple/basic instructions to get started.
Facebook itself has the basic settings listed. However, the settings you'll use depends on power of your computer, and what you are trying to accomplish (ex have higher resolution base canvas as you plan to record locally, then re-encode for 720p to FB. there are trade-offs with all these choices. I redid my settings a few times (completely) after first handful of streams. Then again when I switched to more powerful computer)
Then there are the guides on using Facebook live itself (having nothing to do with OBS), as well as the all-important to understand implications of Scheduled vs non-scheduled. And then the requirements for Scheduled live broadcast (connecting well in advance of scheduled time)
The beauty of OBS is that it is free and powerful. With that comes complexity and the onus on the user to research and understand it (RTFM..so to speak). Personally, I found the audio aspect of OBS the most confusing, and finally cleaned things up when a friend recommended disabling all the default Audio devices in Settings, then adding audio source per scene as needed (no Desktop audio)... but that won't work for plenty of streaming scenarios.
My recommendation - start using Facebook Test broadcasts using /live/producer and keep it REALLY simple. Can you connect stream at all?
Have you tried Recording in OBS (not streaming) and checking that recorded file? - that will tell you (without streaming/FB complications), if you have the OBS mechanics working
If you have a specific question, please let us know. The # of settings in OBS to enable connection to FB stream are quite limited (ie lots you can do, but only a few after initial setup for streaming truly required). Have you looked in the Guides section under Resources
https://obsproject.com/forum/resources/?page=2