L3DT is not available for Mac but there are a few alternatives that runs on macOS with similar functionality. The best Mac alternative is Terragen, which is free. If that doesn't suit you, our users have ranked more than 10 alternatives to L3DT and four of them are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to L3DT are Vue (Paid), Natural Scene Designer (Paid) and VizTerra (Paid).
VizTerra is fast, powerful 3D Professional Hardscaping and Landscaping design software. VizTerra gives you the power to quickly and easily design incredibly detailed, fully-interactive 3D hardscapes, landscapes, and outdoor living spaces.