Hi! I was having difficulty too but I figured it out. This method worked on Windows, so I'm not sure how it will fair on Mac or Linux, but I think it'll still work.
Download the "Highway_Blossoms_Remastered-2.54-all-ages-win" version of the game & download the 1.1.1 patch
Then extract both into desired place
Go into the extracted 1.1.1 patch and copy "adult.rpa" - the other file does not matter
Then go into the extracted "Highway_Blossoms_Remastered-2.54-all-ages-win" and locate the folder "game" and open it - the folder should be roughly 847 megabytes
then just right click and paste "adult.rpa" into that folder
restart the game and go into preferences and it should be there under Transitions - just click the box
hope this helps!