Hello Sarah,
I apologize for the delay response, this slipped through the crack.
1) Are you running this inside the AppStudio Player on the phone or using the built app? If this is inside the AppStudio Player, this should not happen, it should work in the desktop and on the phone inside the AppStudio Player. I have a feeling it might have something to do with WebMap that is being used, where it might not be accessible from the network which the phone is connected to.
2) When a Story Map Map Tour is created, we need to provide the two fields for images: "thumb_url" and "pic_url", many "thumb_url" have poor resolution, which why it looks blurry on this case.
If you have access, you can change the "thumb_url" in the Story Map Map Tour to a better resolution image, or you can go to the Setting of the Map Tour template in AppStudio to override the Thumbnail URL to use the "pic_url", see image below.
I hope this is helpful,
Erwin