Run the activator tool as an administrator by right-clicking on the executable file and selecting "Run as administrator."
If you must access SolidWorks files or features on a Windows 11 machine, there are several legal and secure options available depending on your budget and use case. solidworks 2016 activator windows 11 upd
If you cannot legitimately activate SolidWorks 2016 on Windows 11: Run the activator tool as an administrator by