for user role:
[fileup sub="sub1" showto="administrator,editor"][fileup sub="sub2" showto="author"][fileup sub="sub3" showto="subscriber"]
If it’s based on a specific user, you can create custom user-meta for your users. So, create a user-meta called, for example, “fileaway-subdir”, then for the relevant users, set the value of that user-meta to be the name of the sub-directory. E.g., users 1, 5, and 25: fileaway-subdir would be “sub1”, but for users 2, 3, 4, and 75: fileaway-subdir would be “sub2”. Then in your shortcode, you simply do this:
[fileup sub=”path/to/fa-usermeta(fileaway-subdir)”]
Then whoever is logged in will have an upload directory pointing to whatever the value is for their user-meta key.