Query 1: I went to that directory that you stated and there is only XML files in there. There are no dll's. Is that directory correct?
We have shared the screenshot of the previously mentioned directory in which you may found the Syncfusion dll’s for the Universal Windows Application.
Location: C:\Program Files (x86)\Syncfusion\Essential Studio\22.214.171.124\Assemblies for Universal Windows\10.0
Please refer the below screenshot for further reference.
Query 2: I would also have to add what DLL's for SfTextBoxExt?
As mentioned in our previous update, we request you to use “Syncfusion.SfInput.UWP” and “Syncfusion.SfShared.UWP” for SfTextBoxExt control. Additionally, please refer the below documentation link to know the assemblies which has been used for the Syncfusion controls.