I should also caution the user about the risks of downloading from untrusted third-party sources. Even if a direct link exists, it might not be safe. Official sources are the safest bet, even if the process is a bit involved.

Also, there's the Apple Developer website where developers can access older versions. If the user has access to a developer account (either personal or company), they can download from there. But if they don't have one, that's another hurdle.

First, I know that macOS Yosemite is an older version, released in 2014. The specific version they want is 10.10.5, which is a later update. They might need this for compatibility reasons, maybe for an old app or hardware that doesn't support newer macOS versions.