A computer or device with the following is required:
64-bit operating system
1GB RAM or better
The following are not requirements, but recommended:
Dual-core or better CPU
PocketMine-MP is notoriously bad at multi-core usage. If purchasing a machine to run PocketMine-MP on, prefer higher CPU frequency instead of lots of cores.
We officially try to support Windows, Linux and MacOS platforms. However, in general any platform which will run 64-bit PHP with the required extensions will work.