You don't generally use articles with Permission. I got permission I received permission. I was granted permission. I obtained permission. I gave permission / I gave my permission. However, in rare cases, e.g. technical work, a permission is sometimes considered an object. "I added the permissions you needed to access the file" or "There is a special permission needed for this function"

Well technically neither are correct. The second sentence is closest though. "got" is not the grammatically correct verb to use, "I received permission" is more appropriate given what little context I have. When you use the pronoun "a" you are making "permission" an object, when it is really more of an abstract idea.