No valid A or AAAA records could be ultimately resolved for mail.adventure-city-roleplay.de. This means that Let's Encrypt would not be able to connect to your domain to perform HTTP validation, since it would not know where to connect to.
No A or AAAA records found.
The IANA public suffix is the TLD of the Registered Domain
The TLD for mail.adventure-city-roleplay.de is: de
The current status.io status for Let's Encrypt