So the error was not actually
'softwareserial' does not name a type
after all
Why are you trying to use SoftwareSerial when the Uno Minima has two hardware serial ports ?
Serial is a direct link between the processor and the PC using USB
Serial1 is a serial interface on pins 0 and 1. Connect the player to pins 0 and 1 and use Serial1 to control it
If only you had told us which board you were using earlier in the topic