"This app does not have access to your photos or videos.”
That happens when iOS asks for access to camera, mic and photo library and user clicks “No” for any or all of the three.
So you would need to
1. go to Settings->Privacy->Photos and make sure WeddingMix has the switch next to it turned on (slid to green color)
2. go to Settings->Privacy->Camera and make sure WeddingMix has the switch next to it turned on (slid to green color)
3. go to Settings->Privacy->Microphone and make sure WeddingMix has the switch next to it turned on (slid to green color)