How to change Modern Player to Classic Player

The error message indicates that the file has Dialog Layers, which aren't supported in the Classic Player. So you have to check all layers on your slides. If any are Dialog layers, switch them to standard layers. 

• https://www.articulatesupport.com/article/Storyline-360-Dialog-Layers  

You also need to check the Feedback Masters, because one or more of those may be set to show as a Dialog layer.

• https://www.articulatesupport.com/article/Storyline-360-Using-Feedback-Masters