This long running deal has been running for a while but never posted for Krispy Kreme SA so thought I'd put it up for those unaware. Similar to the NSW, VIC, QLD, WA deal but with an extra 2 donuts. You must register through the Krispy Kreme SA website linked, as it's a separate company and offer.
Last I saw, you had 17 days to redeem it (10 days before your birthday and 7 days after), assuming you've registered in advance.
You'll need to bring ID and you can't redeem this at OTR Krispy Kreme stores, only stores listed here.
Edit: You'll receive an email prior to your birthday with a barcode, which they'll scan in store.