This article explores the history of ArcGIS 9.3, the dangers of seeking cracked software, the compatibility nightmare of running it on modern computers, and the legitimate alternatives available today.
Esri offers a $100/year Personal Use license for ArcGIS Desktop (current version, not 9.3). This gives you full access to ArcMap (which still retains 9.3-era workflows) plus ArcGIS Pro. Arcgis 9.3 Free Download Full Version
If you're a student, get (often free or very low cost through your institution's Esri license). This article explores the history of ArcGIS 9