We do not have enough details from your original message to make an effective suggestion. Could you tell us specifically about the issue you're experiencing? You can also refer to the questions and suggestions I posted in this thread so I can assist you further.
I had the same problem. Acorn would play for a few seconds and then go back to the Roku home screen. I figured out that Acorn did not like the Roku "Display" setting (in settings) set to "Auto". I changed it to "4K HDR TV" and now Acorn works.