Just finished the 2nd download (7 hours), and it has apparently worked this time. I am indeed using the latest 18.7.0 launcher.
Would still like to know a bit more about why after it is released through Steam I can't somehow transfer my digital rights to play the game to their library (as I personally believe their server performance/modding etc is better from my perspective).
Thanks for the response(s) anyway. Jay / Vyktor.