Is this the latest Delta build?
Yes. The check looks at what your device is running first, then prepares the Delta Executor build that matches it, so you are not given an older package left on a mirror.
Do I need a key to use scripts?
No. The build comes with its script engine ready, so you paste or choose a script and run it with no key step in the way.
Does it work on iOS and Android?
Android, iOS and Windows each have a build of their own. The check picks the one for the device you're on, and you can choose it yourself if you like.
Where do the scripts come from, then?
A script hub comes with the build, so there's a list to run from on the first launch rather than an empty editor.