If your paper requires a section on "Software Acquisition," you should reference the official Esri channels. Using "free download" in search engines often leads to cracked software sites, which are unethical and illegal to cite in a paper.
If your paper discusses the technical feasibility of running ArcGIS 10.8 on Windows 11, you must reference the system requirements. ArcGIS 10.8 was released before Windows 11 existed, which causes compatibility issues. arcgis 10.8 free download for windows 11
If you are a student, your institution likely provides a download link or access to an organizational My Esri account. Minimum System Requirements for Windows 11 If your paper requires a section on "Software