Insufficient storage problems

That's a strange problem, I'm the opposite..I have not enough space....you have heaps.
What you may have to do, just guessing here, is to "turn off" any other apps that are running in the background on your phone as this maybe causing a conflict when trying to down load the Exploreoz Map set.
If you still have issues..you will have to contemplate deleting the Exploreoz Traveller App, close down all your apps running in the background still and then do a reinstall of the Traveller app and see how that goes.
Failing that...contact the Exploreoz Help desk.

That’s an unusual problem Pitty

Try swiping all open app’s closed, clear the cache on the phone and then reboot it.

Regards

TrevorDavid