Put artist, album and title of an audio file into variables

The easiest way to do that is to copy the files as-is (assuming you don't want to move/rename the originals), then use Opus's Rename tool to move them into the desired directory structure.

There's an example of this here. The new name can form an absolute path if you need it to. For example, X:{mp3artist}{mp3album}{mp3title}

If you just want to organise the files without copying them, you can skip the copy stage and use the rename tool directly.