You would need to install R2015b or earlier.
It is an open question as to whether Mathworks would ever release another 32 bit version if you were willing to pay enough money. I like to say that a $2 million non-refundable fee would probably get you a meeting on the topic... but that might just be a Project Manager personally telling you No No No No Not Going To Do That.
Certainly there is no available release after R2015b that is 32 bit.
