The Panopto recorder has hotkeys to assist with your video creation, but they only work in the downloaded application, not the web capture mode.
You can download the application by clicking Create -> Panopto for Windows:
Once the application is downloaded, the hotkey information can be found here (F8 to start, F9 to pause, F10 to end): https://support.panopto.com/s/article/Panopto-for-Windows-Hotkeys