Outlook 365 Meeting Form Add-In

I need a small, focused custom form that opens directly inside Outlook Desktop & Web app as a 365 add-in. The add-in should add an icon on a Meeting Request window, and show a form with multiple fields that the user can fill out. The results of the form should go in the body of a new e-mail.

Core behaviour
• When a user schedules or edits a meeting, the add-in should launch via a custom icon in the toolbar and render the web form.
• All native meeting fields (date, time, participants, subject, body) stay in place, but an additional “Room requirements” form is available.
• On save, the meeting is stored in the organizer’s calendar appointment detail text/body field.

Technical expectations
The project must run across Outlook on Windows, Mac, and Web using the Office JavaScript API, an add-in manifest (v1.13+), and a lightweight HTML/JS front end. If a simple serverless approach (e.g., Azure Functions) is needed for storage or logic, please outline it; otherwise keep everything client-side. Code should be clean, commented, and ready for sideloading.

Deliverables
1. Manifest XML ready for upload
2. Web assets (HTML, CSS, JS) implementing the form
3. Instructions for sideloading, deployment, and future publishing to AppSource

There is currently files that were partially built, however, are not working. Need help to format the manifest file correctly and finish the proejct.