I want to get the SN1 from the bus station to the centre of Granada.

How does the ticket cost?
Where do I buy the ticket, on the bus or at the station?
Do you need exact change when paying the driver?

The SN1 has been discontinued and replaced with the 33.

The price is 1.20 euros.
You can buy the ticket on the bus.
It is best to pay in cash.

It is best to have the exact fare.
They may refuse to take large bank notes.

Just go out of the bus station and the 33 bustop is in front of you.
For the centre of Granada most people get off at the Catedral.
The journey takes about 18 minutes.

There is more info about buses here:
https://granadainfo.com/buses.htm

and maps of the main routes here.
https://granadainfo.com/bus-map-eng.htm

I answered a similar question here
https://granadaforo.com/getting-around-in-granada/what-is-the-best-way-from-the-bus-station-to-plaza-nueva/