Installing Sphinx on Linux
Your best bet is to use the precompiled binaries available on Sphinx’s website - especially if you’re using a v3.x release of Sphinx.
Most Linux package managers do have Sphinx available as a pre-built package, though sometimes their versions may be a bit old. For Debian and Ubuntu, the package name is sphinxsearch. Gentoo’s portage has it available as just sphinx.
The source for the v3 releases of Sphinx is not available, but compiling Sphinx v2.2.11 yourself is an option if you’d prefer to use that.