I read and re-read your post a few times. Apologies if the answer you received to the question you asked was not what you wanted but, this is a tried and true way to verify a pgp key.
It seems that you are confused about Malte’s key and in general as to how pgp keys, sub-keys, IDs & fingerprints work.
Public key infrastructure or, as commonly refereed to as PKI can be a bit confusing for many novice computer users but, the World Wide Web is abundant with MANY great resources for learning about and finding the answers many beginners have regarding implementation(s) of. If the WWW is not one’s cup of tea, the study guide for CompTIA’s seminal security basics/101 Security+ (SY0-601) exam has an entire chapter titled “Cryptography and the Public Key Infrastructure” and can be found in many public libraries as well as via one’s prefered online book vendor.
In an effort to assist users like yourself, the Ubuntu keyserver is a bit more beginner friendly/explicit in what is returned via the web UI. If the https://keyserver.ubuntu.com + gpg@librewolf.net link provided above is used, one is able to drill down to Malte’s key under sub-keys via d29fbd5f93c0cfc3.
Hope this helps make you happy 