tap on
phrasal verbPart oftap
tap on — phrasal verb
1. to touch a card or phone against an electronic reader at the start of a journey
1.phrasal verb
Definition
to touch a card or phone against an electronic reader at the start of a journey on public transport to record the beginning of a trip.
Example
Commuters tap on at the gate and tap off at their destination station.
The machine beeps twice when you tap on successfully with your travel card.