Bandwidth?

Welcome to the Zoom Community, @mfbrown.

Bandwidth required for adequate Zoom meetings is surprisingly small.  See the Bandwidth section of this Zoom Support article for some details:

https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060748#h_d278c327-e03d-4896-b19a-96a8f3c0c69c

Keep in mind that they're talking about your bandwidth, which ultimately feeds your information to (and receives information from) the Zoom Servers, which lie in between you and your attendees.  Zoom has an incredible network of data centers around the world, and while some of your more far-reaching international attendees might see a bit of a delay... they shouldn't notice it, since it should mostly be a consistent delay across continents.

4MB to 12MB should be sufficient.  When possible, use a wired connection to your network, as WiFi congestion is the most often-encountered issue.