windows 10 system .
purchased F- secure on my windows 10 computer . Download stopped at 44% .
Installation getting stuck at 44% possibly means that the protection has detected an incompatible software on your PC. Uninstall the incompatible antivirus program and then install F-Secure SAFE from My F-Secure.
Guide for the installation: https://community.f-secure.com/safe-en/kb/articles/5210-how-do-i-install-f-secure-safe-on-my-pc
You may also use the F-Secure Uninstallation tool so you can start the F-Secure SAFE installation afresh.