Noob question, but I do need help building libvirt-php

So I'm pretty new to PHP, but I just want a simple php frontend that lets me view my VMs from an external computer. Using the download at https://php.libvirt.org/downloads.html and trying to run ./configure gives me this error:

configure: error: Package requirements (libvirt >= 1.2.13) were not met:

No package 'libvirt' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables LIBVIRT_CFLAGS
and LIBVIRT_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.

The hypervisor is running Linux Mint, and the libvirt Debian package does not exist. libvirt0 is installed though.

Using --without-libvirt gives the same error.