Step 3 - Press the through bolts into deck hardware with some good pressure.
First though make sure the hardware is clean, Acetone works well, but if Silicone was previously used you'll really want abrasives as Acetone won't touch dry silicone contamination.
Gelcoat silicone contamination is a whole other subject for a whole other day. Please avoid silicone except for certain tasks involving plastics that require its use.