You can specify any path in the Target Collection Resource URL, as long as it's readable, but if it's a local file, it need to have the "file://" prefix.
Would the same prefix work for iOS?
Yes, the same prefix should be applied on all platforms when reading the file locally.
I'm trying to set the Target Collection Resource URL to Application.persistentDataPath to load a .wtc file at runtime. Is this possible if so what am I doing wrong? I can't put the .wtc file in the streaming assets folder once it's built for android because it only has read permissions.