The Ubidots library currently makes use of softwareSerial.h to emulate ports in an Arduino UNO or some similar board that only has a native hardware port, because this library has problems working at more than 9600 bps and that the ESP module currently works at 115200, you will still have problems with MEGA because our library would continue to emulate the port.
We are working to port this library and enable its use on boards that have more than one native hardware port, without having to look to port emulation.