If you're already familiar with Zoom, it can be a good option to get up and running quickly. Just know that your viewers won't be in Zoom, they'll be in your Uscreen storefront watching. What this means, is that some functionality that's present in zoom like chat and Q&A isn't then shown on the stream in Uscreen.
Think of Zoom in this case, just sending the video to be watched elsewhere.
Zoom will also control the quality of the camera and mic you use which if you're looking for high quality video, it might not be the best option for you, but if you're hosting a video chat with another person in another city it can work great.
If you're looking for something where you control the video and sound quality check out OBS.
In Zoom you'll need to enable Custom Live Streaming Services which is really just enabling the RTMP protocol.
Navigate to Admin > Accounts Settings and click on In Meeting (Advanced)
Then scroll down to Allow live streaming meetings and toggle it on. Make sure you also toggle Custom Live Streaming Service.
In your Zoom meeting, click on ...More and select Live on Custom Live Streaming Service. Enter your Stream URL, Stream Key, and Live Stream Page URL from Uscreen. You can find your Live Stream Page URL under the SEO tab on the live event.
You'll be live and you can go back into Uscreen to test the stream: