I actually got some information on this last week when aa non status family member also didn't have access. Based on terms and conditions, this feature is only available to premier members and chase card members...
1.4. Awards
Merchandise Awards and Headliners Auctions are available to Premier members and/or United MileagePlus Chase Cardmembers who in each case are also members with a MileagePlus account address in the 48 contiguous United States.MileagePlus reserves the right to establish eligibility criteria for redemption of awards. The awards consist of any goods or services purchased by you, by buying or bidding, and sold, auctioned, awarded and distributed by independent partners that make available such awards directly to you via the MileagePlus site. Awards issued are subject to the rules of the MileagePlus program. MileagePlus, its subsidiaries, affiliates and agents are not responsible for any products and services of other participating companies and partners.