If it is wired in parallel you will only get much less than the rated torque with 2.2A. But of course you need less power and the motor will get less hot.
So the needed power per coil is 2.2²x0.4 = about 2W per coil. That's 24W for all coils. Taking into account losses and mechanical work your PSU should be sufficent with 50W.
Things are very different if you use the rated current for theses motors (5.7A): ~13W/coil, 155W overall. And with losses and mechanical work your PSU should be able to deliver at least 300W. But in this case I would prefer to wire the coils in series. According to the needed power it makes no difference, but the TB6600 cannot deliver the rated current when wired in parallel.
I connected blue-red to A+ and yellow black to A-. Should I connect red-yellow to A+ and blue-black to A- (just for A+ and A-, I will connect B+ and B- with the same way)? Thanks for the information.
I was talking about the driver-motor cabling for series connection. Does red-yellow to A+ and blue-black to A- and the same logic for B+,B- make the motor series connected?
I was just trying to make sure.