Thank you for referring to the Lightbend license FAQ. These use grants under the BSL are very limited - here the additional use grant for the Play Framework:

"If you develop an application using a version of Play Framework that utilizes binary versions of akka-streams and its dependencies, you may use such binary versions of akka-streams and its dependencies in the development of your application only as they are incorporated into Play Framework and solely to implement the functionality provided by Play Framework; provided that, they are only used in the following way: Connecting to a Play Framework websocket and/or Play Framework request/response bodies for server and play-ws client."

This won't really work because many projects based on the Play Framework use more Akka features than those granted.