@LDB123Ali Does the pack show as owned in Origin? Open your Origin game library, cllick on the Sims 4 icon, select More > Expansion Packs, scroll down to Discover University, and see what the orange button says. If it says Download, you can do so; Play or Details means it's already installed; Buy Now means Origin thinks you don't own it.
If the pack is downloaded but won't show in-game, the issue may be that you're running the Legacy Edition of Sims 4. All new packs starting with DU won't run in the Legacy Edition. In this case, you can request a refund from EA customer support:
https://help.ea.com/en/contact-us/
Support is on limited hours right now, with phone calls entirely unavailable and live chat only open from 9 am to midnight GMT, Monday through Saturday.
If the button on the pack says Buy Now, contact support to find out why your purchase didn't go through.