Trimble AMP(Account Management Portal)) and SketchUp NZ accounts are two separate accounts and they serve different purposes.
You use SketchUp NZ Account to manage your subscription billing, renewals and account details. You use Trimble AMP Account to download your SketchUp subscription and other SketchUp products.
From your account dashboard you can view your recent orders, manage your shipping and billing addresses, and edit your password and account details.