I installed the trial and tried to convert dxf to 3D PDF in Acrobat Pro 2017, but failed. There is a post similar to my question, and the answer was no. If we look at the version log at https://tetra4d.com/tetra-4d-converter/#converter-formats, Tetra4D converter supports 3D Autocad input. This becomes confusing to me. Any input is appreciated.