When setting up a meeting, it's a hassle to have to switch between Outlook and Zoom to schedule a meeting with a Zoom link. The plug-in helps. It has quirks but makes the process faster and easier.
In Outlook (desktop version), click File, then click "Manage Add-ins"
This will open the online version of Outlook and bring up the "Add-Ins for Outlook" window. On the right side, search for "Zoom for Outlook" and it pops up (before you finish typing), click on it.
Next, click the "Add" button.
Close the web browser windows and go back to Outlook (you may need to restart Outlook to see the changes). Now, when you set up a meeting, you'll see a button in the Ribbon called "Add a Zoom Meeting".
Clicking that creates a Zoom meeting, drops the URL into the location for the meeting and pastes an invitation to the Zoom session into the body of the meeting. Now for the minor quirk. It doesn't update the Zoom information if you change the date or time so always click the "Add a Zoom Meeting" after you set those. Zoom won't care and the link will still work fine, but the pasted invitation will have the wrong date/time on it which can confuse attendees.