If, after uploading a catch photo, the app does not automatically drop a pin on the map, it means that it was unable to read or access the Exif data. This might also be the case if you have copied the photo from another social media app, or if it was sent by a friend who took the photo on their device.
In order for your device to save Exif data in photos, you will need to update your location services / camera settings. Check your device's manual for instructions on how to enable Exif location data.
Read more about how the Fishbrain app uses Exif data in catch photos here.