After reaching hardmode, you can choose the type of the world's evil when generating new worlds. If you have already reached hardmode, just load any pre-existing hardmode world and it will activate this feature.
My wallet was so prepared for this moment. I have already purchased it when I got the email notification from Bandcamp.
It's a shame that we don't get to have console soundtracks due to copyrighted by different company, but we'll have to live to that regardless.
At least I can finally play...