Try and install Plasma from a live medium provided by several Linux distributions.
The latest stable Plasma version is available as a live image as part of the Krypton stable image:
KDE neon builds Frameworks, Plasma and Applications on a continuous integration system.
The user editions build from released software.
Alien BOB (Eric Hameleers) provides an installable Live image for Plasma 5 based on the development tree "slackware64-current". Login account/password are both "live". Use su or sudo to become root (using the "live" password).
Chakra is a GNU/Linux distribution with an emphasis on KDE and Qt that focuses on simplicity from a technical standpoint and free software. The downloadable ISO features a bootable environment that allows you to test the system before installing it.
The Fedora KDE Spin comes with Plasma. New minor Plasma versions are pushed as regular updates for Fedora installations but live media may contain a slightly older release (depending on Fedora’s release cycle).
Kubuntu 16.04 LTS and 16.10 support Plasma 5.8.5 through Backports.
Mageia ships Plasma in Live Images.
You can update to latest Plasma in live mode, even without installing to disk.