To run DropPy you need a Mac running at least macOS 10.12 Sierra. Apple’s latest version macOS 10.13 High Sierra is fully supported.
Running DropPy on prior versions of macOS is not possible. (why?)
As of now there is no version for iOS, Windows, Linux or Android.
Sierra and High Sierra already come with Python 2.7 pre-installed.
There is no need to download another Python interpreter - but you can of course do this. DropPy supports multiple Interpreters (more info).
Some Tasks require Python packages that are not included in the standard library, for example
If a Workflow fails take a look in the log file to see the exact error of the Task. Then just refer to its documentation.