Thanks for reaching out about this in the Community!
Currently Alexa speakers play playlists in Shuffle mode by default. This is not something that can be controlled directly from the Spotify app.
There are other users on the Community who want this to be changed. You can check out their Idea thread here. Feel free to add your +Vote.
Here you can read more on how ideas work.
Hope this helps. Don't hesitate to reach out again if you have questions.
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