Due to my file limit here on Itch, I had to make chapter 5 into a patch - meaning it contains the chapter 5 images only.
In order to play 0.5.1 after downloading, unzip it and copy it into the 0.4.5 folder after unzipping (select overwrite when asked about it), then run 0.4.5 as you normally would. If the top right corner of the main menu screen shows 0.5.1, you've done it correctly.
I have made a post at the top of this page, also on the download page, and in addition to that I answered you message about three months ago when you asked the same question - if you scroll down a bit. :)
If you have problems patching, then you can download chapter 1-5 in one go at my patreon page:
https://www.patreon.com/posts/leap-of-faith-5-50719656
(if you download chapter 1-5 in one go, install it anywhere. your saves are still intact).