It's an easy to miss item in the Rules Reference Guide, pg. 21:
Rebel Upgrade Stage Section:
•To purchase Item cards, Rebel players shuffle the Item deck
listed on the campaign log. Then they draw six cards from
this deck and may purchase any number of those cards of
their choice. Then they shuffle any unpurchased cards back
into the deck.
- If more than one Item deck is listed on the campaign log,
players shuffle and draw six cards from each deck.