If an individual has a paper receipt then you can straightaway walk to the Abu Dhabi Police Station and make the payment there.
And if you do not have a receipt but there rules that you have broken then you can also go on the Abu Dhabi Police Website Portal but for that as well you will have to go to the website and create a user profile and sign in to Investigate. From the website, you can easily check your fines and pay the fines.