Update Dec 2020 - The information below is still valid and can help walk a user through the process of enabling interaction between Zoom and Outlook/Contacts/Calendar. Zoom still continues to offer two options a 'Plugin' as well as an 'Add-in'. The Add-in is probably the best choice for most users but Zoom has created a document explaining the differences between the two types of integration: https://support.zoom.us/hc/en-us/articles/360028360712-Outlook-Plugin-and-Add-in-Comparison
Zoom users can enable the Office 365 Zoom Add-In to integrate Office and Zoom, allowing the Zoom app to see your Outlook meetings and allowing you to schedule Zoom meetings, directly from Outlook.
Zoom offers a list of Downloads available here: https://zoom.us/download
The bottom link to the plugin is a legacy application that will only install on onto the desktop Outlook application and needs to be installed on each PC you will be using. The plugin requires local administrative permissions and if you are using a CCS device, you may not have privileges to install the plugin.
Preferred is the Outlook Add-In which is accessible via the Add Zoom button (as pictured above) or directly through Outlook (web or client application):
Click 'Get Add-ins' and then Search for Zoom, the first option is generally the Zoom for Outlook add-in. Choose to Add it and follow the prompts. NOTE: You may be asked to Sign-in to Office 365 and to authorize the add-in, which you should do.
If you believe you may have installed the add-in already, you can check by clicking 'My add-ins' and seeing if it's listed.
Using the Add-In
You can use the add-in on Office.com or on the Outlook application on your desktop/laptop. Once added, the Zoom add-in is attached to your account and is available on both Office Web and applications.
In Outlook --> New Items --> Meeting and then, on the ribbon across the top, Add a Zoom Meeting. You can preemptively make changes to the Zoom settings with the gear icon, then insert the Zoom meeting into the Outlook invite.