There is a Beginner Group for adults organized by Rand Sportarten:

https://www.randsportarten.at/volleyball/mix-volleyball/

Currently the basic trainings take place on:

Tuesday - 18:30 Alterlaa

Saturday - 18:00 Wittelsbachstraße 6

If you can speak some German you should be able to join with a mixture of German and English.

e-mail Rand Sportarten for more information on the group trainings: volleyball@randsportarten.at 

Beachvolley Wien offers beginner (Basiskurs), and just above beginner lessons (Leicht Fortgeschritten). There are winter and summer courses.

Most of their instructors are able to speak English in addition to German (just ask if they can speak in both languages when you register). 

Beach volleyball is not the same as indoor volleyball, but many of the skills are transferable to indoor volleyball. In beach volleyball you move your feet alot and get many chances to bump/set/spike the ball as it is a 2v2 or 3v3 game. Also, a beach volleyball is lighter and slower moving than an indoor ball so it can really help you learn some skills quicker.

https://www.beachvolleywien.at/training/

https://www.beachvolleywien.at/