hit it off from the start

The Japan Times July 3の記事表題からの引用です。
Princess Ayako says she and fiance Kei Moriya hit it off from the start
"hit it off" は知らない表現ですが、文脈から意味は容易に推測できます。
記事を読むと表題の表現を裏ずけする文章が次の様にありました。
“I met Mr. Moriya for the first time in December last year, and I remember that our conversation got so lively that it didn’t feel like we had just met and that I had so much fun that I forgot about time,” said the princess, who serves as honorary patron of the Canada-Japan Society, a public organization that promotes mutual understanding and friendship between Japanese and Canadian nationals.

"hit it off" を一応辞書で確認します。
・Oxford English Dictionary: Be naturally friendly or well suited.: She met this guy Tim at a party of a mutual friend and seemed to hit it off.
・Collins Dictionary: If two people hit it off, they like each other and become friendly as soon as they meet.: They hit it off straight away, Daddy and Walter.
・Cambridge English Dictionary: to be friendly with each other immediately: We had similar ideas about the show, and the two of us hit it off right away.
めでたしめでたしですね。