When it comes to downloading and sending a MOBI file to Kindle, folks, there's NOTHING to it. I used another code to take screen captures to go along with the instructions so I could do this blog post and direct readers to the post to look at the instructions and pictures if need be.
Go to the publisher's link. This process starts on the publisher's webpage. Copy and paste the redemption code in the space provided. Enter your email address. Check the terms and click submit.
Next screen will open on Enthrill's site. Go to "Know File Format You Need." I put the green asterisks on there. Click on Mobi.
On the next screen, you click on the Download to Computer icon.
On the next screen, just right click on download. I ignored everything else that's written in that box because my plan was to download the Mobi file and email it to my Kindle. When you click on Right Click to Download, you'll get the popup screen to save your file, which is shown in Step 5.
So this is what comes up for your download. Save in your documents. I put the file in a folder named "Books"
Next email the file to your Kindle. I have been emailing Word files and Mobi files once I started formatting for Kindle for ages. If you are familiar with this process, you are good to go.
If you have never sent a document to your Kindle, go to Send to Kindle instructions and set up your email address so the file will load into your Kindle.
Once you have emailed your file to your Kindle, the book will appear in a few minutes in your Kindle. It will be identical to a purchased copy. This is the copy I downloaded to my Paperwhite.
That's all there is to it. It took less than five minutes. Note: You can't use the same process for an epub file like for Nook or iBooks because I don't think they are set up like Amazon to send a file directly to your reader. They require side-loading, which is a different process.