If you are seeing the error "Could not create test write file for Pictures at 'C:\Users\YOURUSERNAME\Pictures\Quill\quillDummyFile.txt'
Please navigate to C:\Users\YOURUSERNAME\ and make sure that the Pictures folder exists. If not - create it. Inside the 'Pictures' folder, create another folder called "Quill" (case and spelling are important!).
If both folders exist - make sure you have write permissions for that location.