2 important points from the FAQ [1]:
Q: Are apps that use the Amazon Mobile Ads API required to be distributed through the Amazon Mobile App Distribution Program?
A: Yes. Apps that use the Amazon Mobile Ads API must be distributed through the Amazon Mobile App Distribution Program before they can be distributed through other Android platforms.
Q: Which regions are supported?
A: The Amazon Mobile Ad Network serves ads to U.S. users.
Also it apparently doesn't play well with AdMob mediation. You have to use custom code to mediate between Amazon and other ad SDKs [2]. No info about which mediator SDKs are currently supported.
[1]: https://developer.amazon.com/sdk/mobileads/faq.html [2]: https://developer.amazon.com/sdk/mobileads/with-other-sdks.h...