Hi there and welcome
You need to free this space up on the C drive on the Aspire, connect a drive does not do this.
Can you move all your photos and videos to the WD drive, and once done, press the windows key + E
Then click on this PC, then right click on C drive and see if you now have 20GB of available space.
Let me know please how you go.
yes, this is what I indicated in my initial message, you need to clear up 20GB from the C drive.
How much have you done so far?