The message is odd indeed if you don’t have another version installed. Maybe contact support and also mention the bug to them so it gets in their system. It should be there but doens’t harm to report.
I’m not sure how high on the priority list 3D paint is right now but if you like to add wear/tear and want to be in full control Substance Painter is a really nice tool for such textures.
Takes a bit of time to get used to it but it’s really good in creating realistic wear/tear using things like smart masks which will be based on curvature/occlusion/thickness etc of an object.
Once you know your way around it’s a really fun program to use and weather you export a complete set of textures or just some masks to be used in KS afterwards depends on yourself.
edit
Because the way Substance Painter works, it does need to have an UV-map present. It can automatically fix those but I always try to make my own.