You use the Zoom Phone app to make your Outreach voice calls, but you're not seeing the Zoom Phone app in the Outreach system.
Users using Zoom Phone to make their voice calls in Outreach
Go to the Chrome Web Store and download/add the Zoom Phone For Outreach Chrome extension. After adding the extension, go back to Outreach and refresh the page (or reload the OE extension).
You need to have the Zoom Phone Outreach Chrome extension installed to make Zoom Phone voice calls in Outreach.