English Translation
We had a casual meeting on the crowded street.
Мы́ слу́чайно́ встре́тились на́ ожи́вленной у́лице.
The word слу́чайно́ is written with two accents, but a Russian word can have at most one. (The second should be dropped.) One-syllable words should be written without an accent.
Also, “We met by chance” would be a betrer translation than “We had a casual meeting”.