When uploading files from within an activity, for example, if you are a student submitting an Assignment, or an instructor adding resources using the Activity chooser, you can drag and drop files directly into the Files area. (This avoids the need to use the Moodle File picker when uploading a file.)
Step 1. Click on the File Explorer and move the window so you can see the Big Blue down arrow on the Moodle page.
Step 2. Drag files from your File Explorer Window using your mouse
NOTE: If adding additional files, when you drag a file over the Files area, the big blue arrow will reappear.