I don't know what idiot wrote that library, but the documentation was generated from the code using doxygen. The result is garbage, so the input (the header file, specifically) is junk.
/**
@brief VR class constructor.
@param buf --> return data .
buf[0] --> Group mode(FF: None Group, 0x8n: User, 0x0n:System
buf[1] --> number of record which is recognized.
buf[2] --> Recognizer index(position) value of the recognized record.
buf[3] --> Signature length
buf[4]~buf[n] --> Signature
timeout --> wait time for receiving packet.
@retval length of valid data in buf. 0 means no data received.
*/
int VR :: recognize(uint8_t *buf, int timeout)
That function is NOT a class constructor.
The rest of the comments are probably correct. They answer all of your questions.