You may be asking what file type you need and how to read the ebook on your preferred device. Below is quick information to help, along with more detailed articles to help you read an ebook from my store.
The epub is the most universal format and works with all devices. Below is a list of the devices and links to articles about sideloading an epub ebook.
AZW3 & MOBI
These two file formats are generally only made for Amazon Kindle devices. MOBI was the old, original format for Kindle and AZW3 format is a newer version. However, Amazon has moved away from both file formats since January 2023. But many authors still offer these two file formats for older Kindle devices.
To sideload AZW3 or MOBI, it is best to follow Amazon's article: Learn About Sending Documents to Your Kindle Library.