You need to use the scheduling assistant in Outlook.
JAWS will work with the scheduling assistant in Microsoft Outlook below are some recommendations.
If you use the 365 version please Update Microsoft Office to the latest version.
When using the assistant you may also wish to review instructions from Microsoft here which include the relevant hotkeys:
https://support.microsoft.com/en-us/office/use-a-screen-reader-to-schedule-appointments-or-meetings-in-outlook-4003c262-540b-4461-96df-55939c270ba0#bkmk_checkavailability_win