gnupg – Unable to verify the SHA256 checksum for Focal (20.04) LTS minimal cloud image

I’m attempting to follow the article here:

to verify the checksum provided with the 20.04 minimal cloud image here:

I’m getting an error from the first command:
$ gpg –keyid-format long –verify SHA256SUMS.gpg SHA256SUMS

gpg: not a detached signature

I don’t think the checksum is being verified because of the error and I’m not having any luck finding a solution elsewhere. I have deleted and re-downloaded the files a couple times, so it’s not an issue with that. Has anyone seen this before? Am I missing something?