It should be noted that the word встречать/ встретить means "to meet up (having already known each other)". If you want to say "i met someone" meaning the first time you met them, having never known them before, use the word познакомить(ся)
That would be "We all met up in the park" as opposed to everyone meeting the speaker at the park.
Дуо очень не любит художественный перевод. Тут сплошной канцелярит, страшный сон Норы Галь.
What would be the difference from 'they meet me at the park'? Thanks!
This is the perfective past tense. You can tell because the typical past tense ending of a verb is -л / -ла / -ло (m / f / n respectively) (usually you just chop the infinitive ending, such as the -ть, and then just toss the past tense ending on).
"They meet me at the park" would be Они встречают меня в парке. It is the imperfective present tense of the verb "To meet".