Try and install Plasma from a live CD provided by several Linux distributions.

Plasma 5.7

KDE neon User Edition

In General

Fedora

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).

KDE neon

KDE neon builds Frameworks and Plasma on a continuous integration system for its Developer Edition.

You can use the stable version for builds from Plasma/5.x branches or unstable version for builds from master branches. The user edition has builds from released software.

http://neon.kde.org/download

Kubuntu

Kubuntu 16.04 supports Plasma 5.6.5 through Backports.
Kubuntu CI is a Kubuntu image plus the Kubuntu CI packages using the latest software from Frameworks, Plasma and Applications Git.

openSUSE

openSUSE Tumbleweed ships the latest stable Plasma 5 release.
openSUSE Leap ships Plasma 5 but without live images.
Argon and Krypton are openSUSE live images shipping the latest KDE software from git (unreleased) for Tumbleweed and Leap, respectively.
SUSE Studio Gallery contains various appliances with KDE Plasma desktop.

ALT Linux

Plasma 4 is included with ALT Linux KDesktop official distribution since 5.0;
Weekly updated Regular builds include both KDE4 and KDE5 ones (installable LiveCDs built upon our unstable development branch dubbed Sisyphus).

Slackware

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).