There was a time lag but your message finally arrived.
Your LINE message arrived, although there was a time lag.
The message you sent at 3:00am finally arrived at 6:30pm.
「タイムラグで 遅れてLINE届いたよ」= There was a time lag but your message finally arrived. / Your LINE message arrived, although there was a time lag.
「3:00am に送ってくれた LINE 私に通知されたのは 6:30pmでした」= The message you sent at 3:00am finally arrived at 6:30pm. / I received the message you sent at 3:00am at 6:30pm.
ボキャブラリー
time lag = 時差、タイムラグ
message = メッセージ
finally = やっと、ようやく
arrived = 届いた
sent = 送った
received = もらった、届いた
Your LINE message arrived late due to some sort of delay
この文章が以下のように翻訳されています。
タイムラグで 遅れてLINE届いたよ ー Your LINE message arrived late due to some sort of delay
タイムラグ ー A delay / some sort of delay / a lag
で ー Due to
遅れて ー late
LINE ー the LINE message / your LINE
届いたよ ー arrived / I was notified of
参考になれば嬉しいです。