Open iOS Settings. On the left panel, scroll all the way down until the third party Apps section. You should find your app there.
Tap on the app icon, and the permissions for that app should be visible on the right side of the Settings window. Make sure Local Network access and Location servies are turned on.
Be warned that this will allow more of your personal data to be sent to a server in China. If you don't want that to happen, do not use SeeStar (you should have known this before buying it). There are other smart scopes that use servers in the west.