IF you are trying to add courses to a Mega account, things can get squirrely.
I always download directly from my browser to my Download Folder. I use Firefox, Chrome and Edge. Windows 7 users MUST choose Chrome or Firefox because IE11 is no longer supported by sophisticated sites.
Keep in mind the Course Checker is a wonderfull program but still needs to open a browser when you click the download link. Since you are on Windows 7 choose Firefox or Chrome.
Hope that helps.