Verify Your Download Before Use
Many applications can verify the checksum of a download. To verify your download can be important as it verifies you really have got the ISO file you wanted to download and not some broken version.
For each ISO, we offer a checksum file with the corresponding SHA256 sum.
For extra security, you can use sha256sum to verify who signed those .sha256 files.
It should be AD48 5664 E901 B867 051A B15F 35A2 F86E 29B7 00A4
Your download is fine. The sha256sum file for the download gives the same value.
The web page is poorly worded. It is trying (but failing) to say that there is a gpg signature available for the checksum file. And the value that you see there (“AD48 5664 E901 B867 051A B15F 35A2 F86E 29B7 00A4”) is the fingerprint of the gpg public key used to check the signature.