Learn Swedish: Jag möter dig vid stationen. - I will meet you at the station.

In Swedish, it is very common to use the present tense to talk about the future, especially when an event is already decided or happening soon. You could say jag ska möta dig, but jag möter dig is shorter and sounds perfectly natural.

Could I use träffar instead of möter in this sentence?

It depends on what you plan to do. Möter usually means meeting someone who is arriving, like picking them up or greeting them. Träffar is used when you are meeting up to spend time together, like having a coffee. Since you are meeting at a station, möter strongly suggests you are there to pick the person up.

Why do we use the preposition vid here instead of på?

Vid translates roughly to "by" or "at the general location of." Saying vid stationen means you will be waiting in the general area, perhaps right outside the main entrance. If you used på stationen, it would mean you are specifically inside the station building or waiting by the tracks.