You need to register as a Secured Party Group (SPG) before you can register your security interest. Registering as an SPG is a way of recording on the register who the secured parties are.
Registering your security interest on the PPSR may give you a better chance of recovering a debt if your debtor defaults.
The Personal Property Securities Act 1999 contains rules for determining priority between security interests in the same collateral. It's important to register your security interests as soon as possible. If you don't register your security interests and a debtor is adjudicated bankrupt or is placed into liquidation, secured creditors will be ahead of you when payments are made or assets distributed.
What story could we tell here about why they might register?
Link to related information - such as searching the PPSR - searching the PPSR is a recommended first step before entering into a contract...