ad_asm to stl conversion is most likely related to export of Alibre Design files to STL format, typically for the purpose to produce a file for 3D printing. Alibre Design supports export to STL format just fine, so such export is certainly possible. Unfortunately it appears that Alibre Designs are not supported in 3rd party software, so using the original software is probably the only option how to export or convert ad_asm to stl.
Updated: January 4, 2023