I installed mine yesterday afternoon. I did it by myself with a little help from my 8 year old. I think what helped me was removing the top ROPS brackets from the windshield and mounting them loosely to the ROPS first. With no windshield attached they slide right into place. I then put the top portion of the windshield on and attached the side brackets loosely first then reattached the windshield to the top brackets. Also, I loosened most of the other adjustment points ahead of time. I was able to align things and then tighten everything up.
I didn’t have any problems with the lower windshield. Based on bigr244’s post above, I was expecting a problem but it went on fine. Not sure why he had trouble and I didn’t. Usually if anybody has trouble like that it’s me. Guess I was lucky this time.