I found this comment and tried using 'arduino' as password and it worked!
ShapeShifter:
Unfortunately, about a year ago, there was a rift between the Arduino founders, and they split into two distinct companies.The original company, making boards labeled with the arduino.cc URL (this forum) have a default WiFi name that includes the word "Arduino" and has a default login password of "arduino"
The newer company, making boards labeled with the arduino.org URL have a default WiFi name that includes the word "Linino" and has a default login password of "doghunter"
Most of the documentation out there is for the arduino.cc boards, which have been around longer. As the arduino.org boards are hitting the market, there is a lot of confusion among the users: most are not aware that there are now two distinct companies selling almost (but not exactly) the same product, and both claiming to be the true Arduino. Sadly, in the end, it's the user community that suffers due to the confusion.