If you would like to share a guest link with someone for a Zoom meeting created through Canvas, you can do so following these instructions. First, you'll need to setup the actual meeting by clicking Schedule a Meeting from the Zoom tab on any course navigation bar:

Once you've setup the meeting using your preferred specifications, be sure to click Save:

Back on the Zoom tab, you'll see your newly created meeting in the Upcoming Meetings section. Click on the blue meeting topic to access the meeting preferences:

From that page, you'll see a Join URL. You can also click Copy Meeting Invitation to copy the meeting URL:

Once you have that meeting link, you're able to invite anyone into your Zoom session, even users without UWP credentials. 

You can also invite users to Zoom sessions that have already started. From your launched Zoom meeting, click on the Participants arrow and there will be an Invite option:

Or, if you already have the Participants sidebar open, you can click on Invite at the bottom of that side panel to invite users into your session that way: