Meaning of おまちする

Question

From: https://www.serebii.net/blackwhite/subwaymaster.png

Context: The character who says this to you (the player) is on the subway along with you. They are also about to battle you.

ようこそ　おまちしておりました！

おまち means "long awaited" from what I can tell, but I'm having trouble understanding exactly what おまちする would mean. Does it mean "to wait a long time"?

What exactly would the full sentence mean then?

Answer 1

お待ちする is the humble form (謙譲語) of 待つ. So お待ちしておりました is the humble way of saying 待っていました, "I was waiting / I've been waiting (for you)." (おります is the humble form of いる.)

For more on the humble form 「お＋連用形+する」, please refer to: Do all verbs have an honorific and humble form?

ようこそ　お待ちしておりました！
"Welcome! I've been waiting for you!"