If you have not determined the source of the noise I believe I can help you. I have two 2016 Haibikes. The bike I ride the most is a Haibike Sduro Hard 7 SL. I currently have just over 7,300 miles on this bike. I encountered the same creaking noise when applying full torque to the crank when starting out or riding up hills. Long story short, it turns out that the holes that are cast in the motor are larger in diameter than the 9mm diameter bolts that secure the motor. I removed the bolts and noticed the wear pattern on the shank of the bolts from the motor shifting under load. As a temporary fix I put some light grease on the shaft of the bolts and re-torqued them. This worked for about 100 miles but at least I knew what the problem was.
As a permanent fix, and I am pretty sure this will void any warranty, I used a 10mm reamer to enlarge the mount holes in the motor casting. I inserted a 10mm stainless steel tube cut to the width of the motor. The inner diameter of the tube is 9mm, same as the mounting bolts. re-assembled and re-torqued the bolts and have not made any more creaking for over 5000 miles now. I believe this is a design error but after numerous phone calls I realized I would need to repair this on my own or live with the noise. The same thing happened on my other Haibike Sduro SM at 1000 miles so I knew exactly what I needed to do. I am 6ft 4 and weigh about 215 lbs so I suspect lighter riders may never encounter this problem.