Go to wondercraft.ai/studio and navigate to the workspace of interest (seeđŸ“„ Navigate to a different workspace). Go to the teamspace that contains the file of interest (seeđŸ“„ Navigate to a different teamspace), then click on My projects.
For instance, I want to move Test voice clip from my Personal space into Test teamspace, both teamspaces under the parent workspace My workspace.

Single left-click on the track and the right hand side panel will open. Click on 'Move to'.

Click the swap icon (circled in red) to move the track from the 'Personal space' teamspace into another one

Choose another teamspace, in this case 'Test teamspace', to move the track to. Or create a new teamspace by clicking the grey button on the top-right

Finally, click 'Move here'