Microsoft released Windows 7 on October 22, 2009, and ended the support on January 14, 2020. Technical assistance and software updates from Windows Update that help protect PCs are no longer available for the product.
Microsoft released the first Service Pack for Windows 7, also known as Windows 7 SP1, in February 2011, just a few days after the release of LibreOffice 3.3, the very first release after the fork. Only the first few versions of LibreOffice could run without Windows 7 SP1, which was turning Windows 7 into a stable operating system by solving 893 bug fixes and 77 security fixes.
In 2020, we still receive complaints from users who cannot install LibreOffice because the system asks them to install Windows 7 SP1. Nine years after the release of Service Pack 1 they are surprised when they are told to update their operating system. Although Windows 7 users are now a minority, the fact that there are people who have unconsciously used their completely unsecure PCs for years is a sign of a global security issue, as these users would not behave in a different way when using a different OS.
Anyway, users who are requested to update their PCs to Windows 7 SP1 can find more details about Windows 7 SP1 and the installation instructions on this Microsoft web page: https://support.microsoft.com/en-au/help/15090/windows-7-install-service-pack-1-sp1.