After you download your project, go to the folder where it was downloaded to. Normally it will be your Download folder is default but you may have changed it.
Find the file.
I normally then right click on that file and pick "cut" and then I right click and paste that file on my Desktop or inside a folder with rest of my books. But to do quick and easy, usually pasting on your desktop is best while learning.
Right Click and choose "Extract All".

Choose where you want the extracted files to go (if you leave it on default, it will just unzip a folder onto your desktop).
Click "Extract".

Then double click on the folder to go inside of it and you will see your Cover.pdf and Interior.pdf, ready to upload on Amazon KDP.

If you need more help, you can watch this video, How To Download And Extract Your PDFs (From A Zip File)
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