Check to see if the extruder connector and the hotend connector are plugged into the proper connections. It is easy for these to be in the wrong place, and the connections look quite similar.
If they are in the wrong spot, turn off the Taz 5. Then switch the connectors so the r-color matches the 4-color, and the 2-color matches the 2. This will fix the max temp error, and you should be good to go!
If not, please contact support@matterhackers.com for further information.