Restart your npm Services
After copying the print folder to C:\DAVID\EXB\EXB2\client\your-extensions\widgets, you would need to restart the npm services.
Note: There are 2 Command Windows.
This one is running npm on the Server:
This one is running npm on the Client:
Enter <Ctrl> C in both Command Windows:
Server
Client
This terminates both the Server and Client npm Services
Start the npm services in both Command Windows with npm start
Server
Client