Part of the process is to extract the file then confirm the MD5 number. How do you confirm that? When I extract the file its only one file which is the firmware file to upload to the router.
The MD5 is a checksum / hash. It's not something that's included in the archive. You extract the firmware file then use a tool on your system to calculate the checksum / hash of the file. E.g. "certutil -hashfile firmware.file md5" in a Windows Command prompt, or "Get-FileHash -LiteralPath firmware.file -Algorithm MD5" in PowerShell. You compare the calculated hash with the one published on the download web page, to confirm that your file is intact.
N.B. MD5 is no longer suitable for security use, it has been deprecated for anything to do with security or cryptography.