Not really sure as it's been a while for me.

But some things to get.

Kindle App on your PC to download the eBooks to your PC.

Calibre and Calibre plugins to remove DRM, and then convert them to the format you prefer.

I think you're good with the Kindle App by itself, but keep in mind those other tools to give you a bit more flexibility.

There's usually free eBooks on Amazon, buy some of those to test the process out to see how it works.