Ring Doorbell 3+ AC or DC transformer

The installation support at https://support.ring.com/hc/en-us/articles/360041599492-How-to-Connect-Your-Ring-Video-Doorbell-3-Plus-Directly-to-a-Low-Voltage-Transformer-Without-a-Pre-existing-Doorbell- tells me to use an AC 24v supply. It says DC is not supported. I have tried using an AC transformer, it made a short circuit and blew a fuse. The Ring transformer at https://en-uk.ring.com/collections/accessories/products/video-doorbell-plug-in-adapter is described as having a 24V DC output and says it works with the Ring 3+ doorbell. These cannot both be correct. I want to get a transformer for direct connection to the 3+ so which type should I buy, AC or DC output?