, indicating it was originally downloaded via Autodesk's official delivery tool. Self-Extracting
If you have legally obtained AutoCAD-2015-English-Win-64bit-dlm-sfx-exe (via an old Autodesk account, a company archive, or a student license), follow these steps precisely.
Specify which of the above (or give a short clarification).
Because this is an executable that downloads remote content, it is a common vector for malware.