Michael O'Neill's side lost their competition opener to Poland at the weekend, but secured their first ever win at the finals of a European Championship courtesy of goals from McAuley and Niall McGinn.
"We had a point to prove to ourselves," McAuley told ITV Sport. "It's pleasing. We've a tough game ahead but we are delighted. Lots of people were saying we wouldn't get a point.
"We thought we let ourselves down with the intensity we played at [against Poland]. We just didn't get that right. We weren't at it against Poland, not to your standards. The lads will take confidence from this because we had been written off."
Northern Ireland will round off their Group C campaign against world champions Germany on Tuesday afternoon.