Status of Austrian German
Austrian German is neither an accent nor a dialect. It is one of the three standard variations of German. The other two standard variations are German German and Swiss German. The situation is similar to British and American English. Non of those two variations of the English language is a dialect or accent of the other one. Also non of the variations of German is a dialect or accent of the other one.
The scientific term for languages with more than one standards is pluricentric language.
All three variations of German are »Hochdeutsch«. (The more exact term is »Standarddeutsch« because Hochdeutsch also can mean the dialects spoken in the south, in contrast to Niederdeutsch which are northern dialects.)
Non of the three standard variations is "more standardized" or "better" than the others. They just have different numbers of native speakers:
- German German: about 82 million native speakers
- Austria German: about 9 million native speakers
- Swiss German: about 6 million native speakers
And of course they differ in vocabulary, grammar and pronunciation (just orthography is the same), but the differences are very small.
What to speak in Austria?
People in Austria are used to German German. All big private TV stations broadcasting in German language are located in Germany and therefore use German German. But they are also consumed in Austria.
And the biggest group of immigrants in Austria are People from Germany. 180,000 persons (of 8.7 millions) living in Austria are Germans, and they speak a mixture of German German and Austrian German, depending how long they are in Austria and how much contact they have to Austrians.
And of course there are German tourists in Austria. In 2017 5.8 Million Germans spent their holidays in Austria. And all of them speak German German.
So we in Austria can understand German German very well. All of us. (The opposite is not true: When I travel to Germany and use Austrian grammar or vocabulary, people often don't understand what I mean.)
So my advice is: Speak what you have learnt. People in Austria will understand you. And if your native language is English, most of us are even able to talk with you in English. (Later is true for Germany and Switzerland too.)