You should have hoisted mast with forestay (not with jib halyard) attached to head of gin poles.  Next ease the main halyard winch to make slack in your side preventor lines.  Once you've done that, (IMPORTANT) run the jib halyard outside the gin poles/bow triangle and attach it to your stem (bow line) fitting; not to the jib tack anchor, and winch halyard taught to achieve your desired shrouds' tension. (I carefully use a socket wrench rachet handle for this, as the tension needed for my snug rig might be more than an aluminum can take).  Then ease forestay tension from trailer winch enough that you can detach the forestay from head of gin poles and attach it to its anchor fitting  (tail?) in bow.  (You won't be short).   Then ease jib halyard tension and detach halyard from the stem fitting and you're done.

I had a similar issue. Rest assured the factory team is only a phone call away and very much willing to help. I am an experienced big boat sailor so the FS headstay was a headscratcher. The underdeck headstay fitting includes a toggle plate and an adjustable turnbuckle for tensioning. I had a block and tackle (old boom vang) and attached it to the jib halyard which I then raised abot 6 feet off the deck. That gave me lots of purchase on the mast to pull it closer to the bow while i attached the forestay. The vang allowed me to lock the jib halyard in one place which avoided cranking hard on the halyard box. That always makes me nervous as the halyard box is expensive to replace.  The factory videos emphasize adjusting the mast rake properly when stepping the mast and I recommend NOT skipping this process. Rest assured when you are successfully finished you will have a much better understanding of the rig.