This is the 409th most frequent Korean word.
있어서
"있어서" means "in/at/having/there is/exists (in relation to)".
Here, '있어서' indicates the existence ('있다') of an issue and connects it to the need for a solution, showing causality between the existence of a problem and the following statement.
여기에 문제가 있어서 해결이 필요합니다.
There is a problem here, so a solution is needed.
Here, '있어서' is used to link the possession of interest ('있다') with the action of joining, indicating a reason.
그는 동아리에 관심이 있어서 가입했어요.
He had an interest in the club, so he joined.
In this sentence, '있어서' relates to the state of being able to remain ('있다') due to a preceding condition ('end of a meeting'), illustrating a temporal cause-and-effect relationship.