In short, no you cannot use folders to organize your project files.

However, you can organize and search for your project files much faster and much easier with Drawboard Projects' Tags functionality.

Instead of adding groups of drawings or documents into a folder, simply:

• select the items you wish to organise,
• tag them with the same folder names (think discipline, project stage, design package etc),
• then add the tag filters to the search bard to find all items that match those tags. 

To add Tags, refer to the Adding Tags article (this works the same across the Web app, Windows 10 app and iOS app). 

To filter your lists by Tags, refer to the Filter by Tags article (this also works the same across the Web app, Windows 10 app and iOS app).