I think the confusion is that some are talking about the actual "strut spacer" used to simply lower the upper mount of the stock (or equivalent) strut and others are talking about the "spacer" lift/level piece they are using to provide lift.
OP.. in those instructions, the piece in photo 36 is garbage. Trash that thing. The piece in photo 37 (the big spacer) is legit.
And yes if you have both, its going to be a terrible ride.
Also, as stated earlier, ALL the standard ifs lifts have strut spacers to bring down the upper mounting location (unless its something like the BDS coilover kit). But even then its the same principal, the lower mount is lowered by 6" and you need some way to bolt the top back in. So either a spacer or you get a strut/coilover that's 6" longer so it fits.