How to apply a new theme on PyCharm?

Question

I can't get to install a theme (plugin) on PyCharm that I've downloaded from the official site.

It's this theme: https://plugins.jetbrains.com/plugin/12100-dark-purple-theme/versions. I've downloaded the latest version (1.1) and I get a .jar file.

I've tried:

1. File > Import settings > select .jar file. This hasn't worked because the .jar doesn't have settings included.

2. File > Settings > Editor > Color scheme > Import color scheme. This doesn't work because the .jar is not a color scheme.

3. File > Settings > Plugins > Install plugin from disk > Select .jar. This has worked to import the theme and I've selected it in the colour scheme section. I've also restarted PyCharm. However, the theme is not being applied.

So... what are the steps from downloading the theme to having it applied on PyCharm?