Problems with SKU_SEN=0539_EN Gravity Voice recognition software

Hallo, i wanted to use subject module with ARDUINO NANO. As a start, i opened the  uart example from the DFRobot.DF2301Q library.

A complilation error came up saying :" no matching funcion to call to DFRobot.DF2301Q_UART(SoftwareSerial*)". Then i tried to compile the I2C equivalent example and it works. Then i changed the board selection from ARDUINO NANO to ARDUINO UNO and the compilation was ok. I cannot find any explanation of this strange behaviour. Please help me. Thanks