I managed to get pocketmine running properly, however I tried to run from src downloaded from github and it gave an error that the spl library cannot be found. It turns out that when I tried downloading the zip file, the folders such as spl and src are empty with no .php files when coming directly from github.
I think you can just run this in the PMMP directory Code: git submodule update --init --recursive if not, just clone with the --recursive option to make sure you get the submodules too.
Git works on Windows too: https://git-for-windows.github.io/ The ZIP doesn't include submodules, if git isn't for you then you can download SPL and RakLib here: https://github.com/pmmp/RakLib https://github.com/pmmp/PocketMine-SPL and put them in their own directories, so you should have this structure within your PM directory, with pocketmine, spl and raklib folders within the src directory: plugins worlds src - pocketmine - spl - raklib