Hey Chris!
Here is an awesome Tech Article that outlines some of the causes of and solutions/workarounds for enabling data downloads in your ArcGIS Dashboard.
Also, when data download is enabled, data can only be downloaded by users who are signed in to an ArcGIS Online account. For dashboards shared publicly that include elements with data download enabled, anonymous users do not see the Download data option on the element.
Let me know if this helps in the error that's generated for you!
Cheers,
Mike