As far as I can see the connections are very straightforward. It needs motor-power and GND and, from the Arduino, 5v, GND and 2 PWM signals, one for FWD and one for REV
I can't immediately see what the Vref pin is for so try leaving it unconnected.
Pin 17 VCC -> Arduino 5V
Pin 16 VM -> 12V DC
Pin 18 FIN -> Arduino Digital Pin 2 (then Digital Write High for Forward?)
Pin 20 RIN -> Arduino Digital Pin 3 (then Digital Wirte High for Reverse?)
GND to GND
I think you have the Driver pins correct. The Uno pin 2 cannot produce a PWM signal. If you need speed control in reverse you would need to use a PWM pin.
If (for example) you want to go Forward then you need to make pin 18 HIGH (or PWM) and pin 20 LOW.