You will be charged automatically after the including 60 minutes have passed.
With extended rental you can have the bike for 3 hours, in addition to the included 60 minutes. After 60 minutes it costs 15 NOK per 15 minutes.
Does the money get drawn from my account automatically?
Yes, if you turn on extended rental. You'll always have a good overview over how long you have been out for a ride and when extend rental starts in the app.