It’s the same save mechanic since the beginning. It’s a manual save that on windows you pull up by right clicking and choose save, then select the box you want to save. There are a lot of pages to save on too, though not sure how to find it on android but works the same.
There are auto saves that will save automatically when talking to the girls, at certain points you have to make a choice, and specific story moments.
Always make sure to have a manual save before you close the game so you don’t lose progress.