I think without knowing the key the developer used, you may be out of luck. You can try using whatever contact you used to get the account access to get the unencrypted source code. Certainly Roku knows how to decrypt the package, but what you have won't do you any good without the key and I don't think it will do you much good even if you have the key. From what I've seen, the encrypted package you downloaded is only good for rekeying the Roku device if you know the key, but that won't get you the source code.
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