What a disappointment! We assembled 90 of the tower. We were on step 15 of instructions where these 2 bars are installed. The plastic pieces had pre-drilled holes for each end of the bars that did not line up with the holes provided in the bars. Further more, the top of the tower with the cute flag then would not fit onto the top of the tower walls or onto the bars. 
After a couple hours of frustration, we settled on attaching the bars with provided screws and accepting that this was as good as it was going to get. 
Thankfully it is sturdy and while our children still love their tower, it has completely sullied our expectations of buying from Wayfair again any time soon.