Details
When using Forms via a web browser Mac, the “Add Question” button doesn't allow any selection (Choice, Text, Rating, etc) to be added. Clicking a selection just brings you back to the Add Question button.
Use the Chrome web browser for working with Microsoft Forms.
Frequently asked questions about Microsoft Forms
Question: Which web browsers with which Microsoft Forms works?
Answer : Microsoft Forms is optimized for Internet Explorer 10+, Edge, Chrome (latest version), Firefox (latest version), Chrome on Android (latest version), and Safari on iOS (latest version).