Yosemite supports the last version of Safari compatible with the OS, but modern web standards (SSL/TLS certificates) have advanced significantly. Users may find many websites inaccessible due to certificate errors. It is strongly recommended to install a modern browser fork if possible (such as Firefox Legacy or specific WebKit builds) or upgrade the OS if the hardware supports it.
If you just need a bootable USB or recovery DMG for Yosemite 10.10.5, download the official installer via Apple’s link above, then extract InstallESD.dmg . That is the proper, safe, and legal way to obtain the file. mac os x yosemite 10.10 5 download dmg