Sorry for the delayed in response, its normal notification because in recent MacOS 10.15 Catalina, security rules have become more stringent. The system notifies you of any attempts to access your data. If an app wants to use data from a particular folder, you should grant access to it within this app, and again confirm this action in the system alert. Currently, macOS Catalina requires that you provide access to your Documents, Desktop, Downloads, and Bin Folders.
You can refer this MacOS Catalina article here and see more information under "Security and Privacy: More User Control Than Ever"
However, its one time permission for F-Secure KEY after successful upgradation of your MacOS. You won't be prompt every time during open the F-Secure KEY.