Unfortunately our community is not localized in Finnish. The community is currently only in English or German.
Concerning your problem using Key on windows XP, please refer to the product page.
The supported platforms are
-Android devices running 4.0 or more recent version
-iPhones and iPads running iOS 5 or more recent version
-Windows 7 or more recent version
-Mac OS X 10.7 or more recent version
XP is unfortunately note a supported platform. Also not that XP is soon not supported anymore by Microsoft.
Have you tried with the latest version (1.4.158)? As mentioned in earlier comments, we are not officially supporting XP but at least on my XP it installs ok and the basic functionality works.