Version 40148 hides the material editor differently than modern versions. Press M inside the Enscape window, or look for the tiny "Editing" button in the top-left of the asset panel. Do not use the external window mode; it crashes on AMD GPUs.
: A streamlined timeline that made creating walkthroughs much faster by allowing users to add keyframes and adjust time-of-day directly. enscape 3d 40148 2021