Java/gradle tutorial doesn't work/run

[quintonn]

Following this tutorial and trying it locally doesn't seem to work:
https://ably.com/tutorials/token-authentication#tutorial-step-7

Just running gradle shows an error because gradle is not installed (windows 10 and ubuntu).
Running gradlew seems to work, as it downloads a gradle wrapper file, but running gradlew build does nothing and shows no output.

I can't seem to run these tutorials at all.
I've spent a couple of hours now fiddling with gradle, something with which i'm not that familiar with.