PowerCore Metro 20000 is compatible with virtually any device on the market. This is due to its USB ports. All current connectors (Micro USB, USB-C, and Lightning) have cables that have a USB-A tip on the other side, so there shouldn't be an issue with compatibility.
On the inputs, it has both a micro USB and USB C port, so the only cable it is not compatible with input-wise is an Apple lightning cable.
If you are having trouble, one of our awesome customer service representatives would be happy to help: 800-988-7973