Here is a simplified solution for you.
- Add your book to Calibre
- Convert it to .azw3
- Download metadata for the right version
- Make sure in the “ids” box you have the id from amazon.com (as shown in the picture)
- If you don’t have the amazon id, just go to amazon.com, search the Kindle version of your book, and copy the ASIN number, paste it into the “ids” box like this:
amazon:[ASIN number]
- Copy the .azw3 to the “documents” folder in your Kindle
You’re now good to go.
You can use Quality Check to check it one more time to be sure.
Quality Check => Fix => Fix ASIN for Kindle Fire (work for other versions of Kindle).
Click “View log”, and it should be something like this:
(Thanks to https://ebooks.stackexchange.com/questions/3644/trouble-hooking-up-goodreads-with-sideloaded-ebook-on-kindle-paperwhite/6187#6187)