Someone was having difficulty parking their car at the parking lot.
この場合、次のような言い方ができますよ。
ーSomeone was having difficulty parking their car at the parking lot.
「駐車場で手こずっている人がいた」
having difficulty parking ... と言う代わりに、
ーhaving trouble parking ...
ーhaving a hard time parking ...
とも言えます。
ご参考まで!