My husband and I are taking our twin 18 year old granddaughters to Salzburg. Arrive on July 21st and leave on July 24th. Would like an apartment with 2 bedrooms. We will have a car. Want to stay fairly near to the Old town. Looking for something between 200 and 400 dollars a night. A/C would be nice and a small kitchen.
Using booking.com and selecting 2 bedrooms, kitchen, parking and a/c in the under $400 range produced 3 results for your dates.
Did not research how close to "Old town' they are.
Without a/c added 5 additional results.
A similar search on Airbnb showed a lot of results which can be winnowed down by adding features like A/C and restricting to a certain city area by zooming into the shown map.
Having a car and staying close to the old town isn't really the best combination.