The Arolsen Archives records have many DP records. Check their website arolsen-archives.org to see what they have put online already. Ancestry.com has indexing some of their postwar lists as well. If what you need is not online, you can submit a search request with them, the United States Holocaust Memorial Museum or Yad Vashem.
The Joint Distribution Committee archives has digitized their DP camp records, https://archives.jdc.org/
USHMM has the Unite Nations Relief and Rehabilitation Administration (UNRRA) Austria mission records but the finding aid is not clear if there a lists of names for Salzburg.