First, Open the Full Grade Center on your Course. After Opening the Full Grade Center, You should click the downward arrow next to the assignment that you want to download. 



After clicking to the downwards arrow, a dropdown menu should open. Click to the “ Assignment File Download” button in the dropdown menu. 



In the opened page, check the boxes that you want to download. After that click to the “ Submit” button at the right-bottom of the page.



Click to the “ Download assignments now” button to download all the assignments that you selected.