Invalid Feed but Validator say is valid?

HI – I am trying to add this feed:
https://radiotamazuj.org/en/rss/news.xml
The plugin refuses it saying Invalid feed URL – Double check the feed source URL setting above.

The Validator gives:
This feed is valid, but interoperability with the widest range of feed readers could be improved by implementing the following recommendations.
line 154, column 2: Missing atom:link with rel=”self” [help]

Is there anything I can do please?

TIA
Julian

http://wordpress.org/plugins/wp-rss-aggregator/