There are two ways you can get this access code for exclusive events.
The first is by being a silver-level supporter on my Prateon/subscriber. That way, whenever there's a new update, you'll find the (current) code in the game's update posts.
The second is to donate a minimum of US$5 here on itch. The donation option is on the download button!
That way, you'll receive the code for version V0.60 of the game by email!