Meaning of "get on"

[Selante]

English Language Tests, Intermediate level

ESL/EFL Test #163 "Idioms with the phrasal verb get", question 4

Train passengers wishing to go to the football match were advised to ......... the train at the next stop.

(a) get on with
(b) get off
(c) get in
(d) get on

English Language Tests, Intermediate level

ESL/EFL Test #163 "Idioms with the phrasal verb get", answer 4

Train passengers wishing to go to the football match were advised to get off the train at the next stop.

Correct answer: (b) get off
_________________________

what does get on mean?

Selante

[Conchita]

To get on:

1 - to mount: he got on his horse; they got on the bus.

2 - to age: he is getting on (he is past middle age).

3 - to succeed: he got on so well in the company that he became a director.

4 - to get on with someone, to be friendly with someone: they don't get on (they don't like each other).

[Saneta]

why not the possibility: get on?

thanks