You can just register and roll to receive NXT for free.
The site aims to give out NXT so that you make your first experiences with NXT and try out trading.
NXT is a new cryptocurrency but has a huge amount of new features.
You receive small amounts every time you roll, so you have to spend some time on the site.
But within one week you can easily get some NXT and see what you can do with it.
This whole service is for free, you do not have to deposit (and cannot in any way). Just make your own NXT account and register with it. No strings attached.