If your interface does not have DSP capabilities, then you have to use something like OBS and, personally, I found that fairly tedious. You have to use something like "Virtual Cable" to then expose the OBS-processed audio as an audio source in Zoom (at least on OS X - it may be built-in for the Windows version).
Adding software FX will possibly introduce latency, so then you will want to also send your existing webcam through OBS so you can correct for that latency (by delaying the video) and then use the OBS [virtual] video webcam in Zoom, instead of the "real" one. Like I said, it can get tedious.
I spent a fair amount of time wrangling this stuff and in the end only used OBS to manage two video streams, and just use the audio direct. (I did use slight compression DSP in my Steinberg UR-44c.) There was some slight, visible latency on a camera going through a "camera card" but it was at a distance where the audio sync was not important.
Personally, I would not bother, because if you have so much background noise you need a gate, it's going to be really obvious, and it would be better to address the problem. There are not many other FX that would make sense (to me) in a spoken word kind of meeting. For a musical performance, maybe you'd want some compression or limiting, but Zoom does do that to some degree. You may want to enable the "original sound" option [in Zoom] for better fidelity, but it depends on the kind of use case, e.g., music performances.
