Zoom is very conservative in bandwidth use on all platforms 1).
Zoom uses up to 1.5Mb/s for gallery view in a regular group meeting. Around 150kb/s for screen sharing and 80kb/s for audio.
For Webinar up to around 1.2Mb/s for video, audio and screen sharing the same as above.
This can be cut to about half by switching down from HD to HQ video quality.
On mobile platforms Zoom follows Apple standard recommendations of no more than 1Mb/s 2)
For H.323 connections the NORDUnet installation supports up to 2Mb/s per video stream.