Hello may i ask why when i download it it come out as install and not update bro?
Ren'py packages games like this and requires a new install.
You can manually transfer saves between versions though, as long as they're not too outdated - (Usually 1 version difference.)
I talk about it in the change logs, about outdated saves from older versions can cause progression bug issues.
If you ever have an outdated save though/lose your saves, you can always just skip to the act you want to play when making a new game.