Your Council is executing a 'recurring' transaction, not an installment - slightly different.
The transaction types are
Sales (POS) - where and Authorisation and Capture (Settlement instruction) happens same time
Authorisation Only with delayed capture - think hotels. They Auth first, the send a capture message later
Pre-Auth - to see if money is on the card
Installment - take a single payment amount and with the consent of the acquirer and issuer break it into several auths that are pre-authorised by the issuer, such that the merchant is not out of pocket if the card is cancelled or card is out of funds at time of installment. These are called "split payments" under the scheme rules, and have been around since the late 1990's.
Recurring - where a similar amount is charged on monthly or quarterly basis (needs CVV each time)
Subscription - where the same amount is charged monthly or quarterly (doesnt need CVV)
Multi Sequence Clearing - where the Auth can be exceeded by up to 15% of the original sales amount, and the Captures can be adhoc up to the Auth+15% value within 9 months of original Auth date
These are called slightly different things by different card schemes, but the above should give you an idea.
All of the abobve can be verified independently by anyone minded to do the research. The Visa Rules are public, as is IP Australia's Government website rejecting the Splitit Australian patent as not being novel. Its not novel, as teh industry has been doing it for years outside of Australia.