After downloading the .ipynb notebook file from D2L you should move (not copy) it to the directory you’ll be working from.  But this leads to another issue: you need to start Jupyter in a directory above that directory so that Jupyter can access it.

Here’s what I suggest you do in the lab:

• Press the Windows key on the keyboard
• This brings up a search box
• Type the letters ana
• This brings up a number of search results
• Click on the “Anaconda Prompt” link (not the Anaconda Navigator link)
• this opens up a command prompt window
• Type the letter of the drive where you moved the notebook file followed by a colon (:) and <enter>.  This will typically be H:,  but possibly E: for a flash drive or D: for the PC’s D drive.
• The prompt should change to indicate you are on the correct drive
• Type jupyter notebook <enter>
• The jupyter notebook interface will open with a file browser at the root of the selected drive

Click on the floppy disk icon periodically to save changes to your notebook.

When you're finished, use the menu item "File -> Close and Halt" to stop the background server process and close the browser window.

Upload the .ipynb file to the correct dropbox.  Check the timestamp on the file (on the disk) to make sure you're uploading the modified version, not the version you downloaded.