Thank you for contacting the Telerik support system.
You have indicated that you are using the Windows client, so I will base my reply on that information.
You can manually add the XHDPI and XXHDPI resources to your project. There are two ways you can approach this task, so I will start with the easier and quicker one.
Approach #1: Using the In-Browser Client
This approach requires you to use another client and not the Windows client for this particular task.
1. Close the Windows client and open your project in the in-browser client.
2. In the Project Navigator, expand the App_Resources directory.
3. Right-click the Android subdirectory and select Add -> New Folder.
4. Name the folder drawable-xhdpi.
5. Repeat step 3 and name the new folder drawable-xxhdpi.
6. Place the xhdpi and xxhdpi resources in the corresponding folders.
7. If you are using version control, commit and push changes and close the in-browser client.
8. Run your project in the Windows client and continue your work.
Approach #2: Using the Windows Client and Third-Party Version Control
1. Configure your project for third-party version control
and push your project to the repo.
2. Clone the remote repository locally on your system.
3. In the local copy of the repo, manually create the drawable-xhdpi and drawable-xxhdpi directories in App_Resources -> Android.
4. Place the xhdpi and xxhdpi resources in their corresponding folders.
5. Push changes to the remote repository.
6. In the Windows client, pull changes from the remote repository.
In addition, you might want to visit our feedback portal and vote for this feature request
which will let you modify App_Resources in a more straightforward way from the Windows client.
Hope this helps. Don't hesitate to let us know if you need more help.