SHIFT allows you to rearrange folders inside a project by moving them:
or by moving them through the project tree:
You can also move or copy assets between projects. Copying assets from one project to another creates a new reference, and does not consume additional storage.
To move or copy an asset between projects, open the projects tree then click and drag the asset onto the desired project. A menu will ask whether you would like to move or copy.
SHIFT allows for a new subfolder to be created from a selection of assets. To do this, select the assets you would like to include by either lasso selecting with the mouse or using Control on your keyboard to select individual assets.
Once you have selected the assets, select the Add Folder icon in the upper right. Name the folder and press Create. The files you have selected will be automatically moved to the new folder as confirmed by the popup message.