Took me about 2 1/2 hrs myself but although it’s been a few years I’ve done it before as well.
A couple pro tips…
In case they didn’t mention where you bought it Otter added marks on the sleds themselves that show exactly where to drill holes.
Like Phil mentioned It is very easy to strip the self tapping screws so put them in gently
For that reason I always wrap the screws on the frame with electrical tap in case I did over (or under) tighten a but they won’t vibrate loose.
Also when putting on the fabric leave the Velcro straps nice and loose to allow some movement of the fabric on the frame.
Will