NetNewsWire can't find that feed.

"Can’t add a feed because no feed was found."

I used the RSS validator at w3.org

https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fww...

This feed is valid, but interoperability with the widest range of feed readers could be improved by implementing the following recommendations.

line 1, column 10821: Missing atom:link with rel="self" [help]

... category><category>Web</category></item></channel></rss> ^