This is the 3240th most frequent Turkish word.
girerken
"While entering" or "as entering."
Here, 'girerken' is used to denote the act of entering that occurs concurrently with the action of talking.
Okula sabahları girerken arkadaşlarımla konuşurum.
I talk with my friends while entering the school in the mornings.
In this sentence, 'girerken' designates the timing of the rain coinciding with entering the house.
Eve girerken yağmur bastırdı.
It started to rain heavily as I was entering the house.
The term 'girerken' here implies performing an action (preparing tickets) during or just before the act of entering.