The 2021 version was notable for several updates over previous years:
SIS 2021 was a bridge release—more advanced than legacy DVD-based versions but before the full cloud migration seen in SIS 2.0. cat sis 2021 download
If you are a legitimate owner of a CAT SIS 2021 license (perhaps from a dealer closing or a fleet auction), here is how to properly install it. The 2021 version was notable for several updates
Even with a legal copy, you cannot "download" the database from the internet. You must have the physical media or a verified image from your Cat dealer. cat sis 2021 download