I'll meet you outside the main entrance

  1. I’ll meet you outside the main entrance.
  2. I’ll meet you outside at the main entrance.

Question: I saw a sentence, the first one from a dictionary. I’m wondering if it’s okay to use a preposition here, like the second one.

Thank you!!!

The first is fine. I think for the second, you’d have to separate it with a comma, but I’m not 100% sure:

I’ll meet you outside, at the main entrance.

Someone might correct me here.