Hi Emanuele,
Thanks for contacting Syncfusion support,
The “Application.Designer.vb file” will be created inside the “My Project” folder in your project location and it is not included by default in the project. You can add it into the project and registered licensed key as suggested in our user guide document.
Also, Syncfusion license keys are version and platform-specific and the generated license key is just a string that needs to be registered before any Syncfusion control is initiated.
Please let us know any assistance on this.
Regards,
Jeyaseelan M