TikTok GST fraud hit on Tax Office blows out to $4.6B

wait a minute. How can you "claim" refund of a tax amount that was never paid in the first place?

by saying you are a registered person and you have made some fictitious expenses on which tax was paid, don't you have to produce those bills? don't those suppliers have to show your registration number as a counter party to make a paper trail? don't you have to show how you actually paid that supplier money from your bank first?

The article seems scant on details which i assume are because the whole thing relied on automation and people found a way to game the system. Is there something i am missing?