how can i size Kiwi Cat tool?

https://documentation.solarwinds.com/en/success_center/kct/content/system_requirements/kct_3-12-3_system_requirements.htm

The requirements are pretty light.

Cat tools is intended for network gear.  It supports custom devices so if you really wanted you could rig it up to do things on any server that responds to SSH, but you'd be pretty much on your own to figure that scenario out. That's not what they really intended for it.