If you looked up the announcement on ASX, you wouldn't see the VAC, but if you got the email or letter, than it should include it.
I think it's not HIN but a unique code generated for you - 'Voting Access Code'.
From the email:
Account Name: MR ##### #### ######
STEP 1: Visit https://www.votingonline.com.au/crowdmobileagm2018
STEP 2: Enter your Postcode (if within Australia) OR Country of Residence (if outside Australia)
STEP 3: Enter your Voting Access Code (VAC) - ######
STEP 4: Follow the prompts to vote on each resolution
CM8 Price at posting:
3.2¢ Sentiment: Hold Disclosure: Held