Each Creek speaking community maintains its own peculiar accent, vocabulary and conversational idiom. Each thinks it is the best and the rest, always suspect, are not quite so correct. Although it may vary from place to place, the written language is never quite so expressive as the spoken word in any community. The written word, at best, is only a shadow of its language.
Shadows never do more than outline or define the shape of things.
To catch a shadow, catch the thing. These written lessons will aid you immensely. However, from these lessons you cannot actually learn a Muskogee language. Only you can teach yourself a language. And, you can only do that by attempting to communicate in that language at any level, even if it is only knowing and using a few words.