Most activation cracks require users to completely disable their antivirus software and Windows Defender during execution. This leaves the operating system completely defenseless against background payloads.
Autodesk offers free access to their software, including AutoCAD, for students, educators, and educational institutions. You simply need to verify your institutional enrollment.
Go to your system's Control Panel or Settings app and uninstall any unfamiliar programs that may have been quietly bundled with the download.