The Zoom web portal (https://uiowa.zoom.us) is your central hub to review and update such things as your profile, meeting settings, and run your meeting reports. You can also use the web portal to schedule, view, and edit meetings. If you use Webinars, the web portal is the only location to schedule and edit them. It's recommended to log into https://uiowa.zoom.us before you start scheduling meetings and review your account features by clicking on Settings on the left hand column. From there, you can review and enable/disable the features you may want to use, such as waiting rooms, annotation, nonverbal feedback icons, etc.
Please note: Some of these options change your default settings, but may be changed in a scheduled meeting's settings. Any features that are disabled (by yourself or the UI Zoom admins) on this page will not be available to you in any of your meetings or webinars.
The Zoom desktop and mobile apps are great for scheduling quick meetings, seeing what meetings you have coming up, and allow you the best experience when joining a meeting. These should be thought of as an extension of the web portal. They can allow you access to some of the web portal settings, but are mostly used for joining meetings.
More information including a table comparing the features between the Zoom desktop client, mobile app and web client can be found here.