Well you start by reading this Install /e/OS on a Samsung Galaxy S7 - “herolte”.
Seeing that you are using Windows there is also [HOWTO] Install /e/ on a Samsung smartphone with Windows easily.
Let’s say that the e-Recovery you downloaded is no good and let’s go for TWRP.
Download site Samsung Galaxy S7 (Exynos) – download the most recent from here Download twrp-3.7.0_9-1-herolte.img. Use this in place of e-Recovery.
TWRP is shipped with a sha256 for twrp-3.7.0_9-1-herolte.img – this is used to check that the download is an exact match with the original. Try this SHA-256 Checksums Explained
Half of the job is to get a working Recovery. Once you have working Custom recovery (another description of TWRP) the second part of the job is easy.
You can use
e-latest-s-herolte.zip and
e-latest-s-herolte.zip.sha256sum
providing you can establish a sha256sum match as above.