Please note that if you are buying a Club membership where the requirement is tier 2 and you are buying a tier 1 AU Membership - complete the purchase of the AU tier 1 membership first! - you do not need to buy a tier 2 membership if you have a tier 1 membership

You must complete the purchase of an AU Tier 1 membership and wait until it has gone through before trying to add a membership where the requirement is tier 2.