is no longer available as a free or supported download from its official developer, Autodesk . Since Autodesk acquired Delcam (the original developer) and subsequently discontinued the ArtCAM line in 2018, official downloads are generally limited to versions 2017 and later for existing license holders. Current Status of ArtCAM 8.1
If you are looking for software with the same artistic CNC capabilities as ArtCAM, several modern options are available: artcam pro 8.1 free download