The word amicable has two possible meanings, depending on whether it is used as an adjective or an adverb.
As an adjective, amicable means friendly and cooperative; showing a willingness to work together towards a common goal. For example, "We had an amicable conversation about the matter." This usage of the word implies that both parties were able to discuss their differences in a civil manner.
As an adverb, amicably means in a friendly and cooperative way; showing willingness to work together towards a common goal. For example, "We resolved our disagreement amicably." In this usage of the word, it implies that both parties were able to come to an agreement without any hard feelings or animosity.