Autosketch 2.1 is a legacy application (released in the mid-90s), and getting it to run on Windows 10 can be a challenge. However, there are several "useful features" regarding how to make it work and what modern alternatives exist if you cannot.
Are you trying to install the program for a new project, or just looking to open and convert old drawings? How to install Autosketch 2.1 under Win 7 XP Mode? autosketch 2.1 windows 10
Before 2019, Autodesk allowed license transfers for very old software. You could install Autosketch 2.1, then apply a patch. This no longer works. Autodesk has discontinued support for any Autosketch version prior to 9. Do not waste time looking for an official Autodesk patch. Autosketch 2
SKETCH.EXE. Set the "Start in" field to the folder containing SKETCH.INI.[autosket.exe]
EMS=0
XMS=0
To install AutoSketch 2.1 on Windows 10, users may need to take a few extra steps: Cause: Working directory is wrong