I have searched Google maps and found none, but I saw that in my city many bus stops are not marked, so I hoped you could help me. Less than 300m from public transportation would be great.
I am disabled and moving to Vienna.
You can search for stores on the Starbucks site, here are the results for Vienna, Austria. There are many stores and many are near U-Bahn stations and/or tram and bus stops.
and a close up showing the tram stop:
But there are plenty others that may be more convenient for you.
AND, although I'm a Starbucks fan myself, I'll point out that Vienna has plenty of other coffee shops that and excellent public transport. So you'll be able to find plenty of choices ...
I notice in the comments that you're looking for somewhere to sit and work.
Apparently, Vienna has a very high concentration of co-working spaces purpose-designed for the sort of thing you're looking to do. From this article:
Move over coffee shops! The Viennese have found a better place to work, connect, and stay warm: Austria may be small, but ...[has]... one the highest number of coworking spaces per capita in the world, many of them are located in the country’s capital.
It lists 12 coworking space initiatives (so at least one is likely to be accessible), three of which are part of a network called Konnex which also offers members:
...an additional range of local services, such as car sharing or “Gemüsekistl” (fresh-delivered vegetables)
Some of these services might be useful to a disabled newcomer to a city, and initiatives like co-working spaces of like-minded pro-community people like this are likely to be a better way to make useful contacts and friends in a new city than Starbucks.
In my experience, the kind of people who join and run initiatives like this will be very enthusiastic about helping a newcomer with specific needs to settle and be productive in their city.