Welcome back to the Wefugees Community and thank you for reaching out to us.
Unfortunately, I am not too familiar with the respective Austrian rules and regulations. But if you check this website by the Austrian government, you will find more information on marring in Austria as a foreigner and a list of all required documents. As I also don't know about your individual situation, it is very difficult to give any tailored advice. I would recommend you to consult a migration counselling office, which offer confidential and free of charge services. Please find a list of organisations on the UNHCR website or on this governmental page (in German though).
All the best,