@SolarDuder , welcome to the Community.
The memory that you bought is recommended by Crucial Memory to work in your computer. Here is the memory on their website: https://www.crucial.com/compatible-upgrade-for/hp---compaq/hp-20-c020t-all-in-one
You should use CPU-Z to find the manufacturer and timings of the HP OEM memory: https://download.cnet.com/CPU-Z/3000-2086_4-10050423.html
This information is in the section titled "SPD". Once you have this information, you should contact Crucial's Tech Support to assure that it is compatible with their memory. You may have to remove the original 4 GB and buy another 4 GB of their memory for it to work.
Please click the Thumbs up + button if I have helped you and click Accept as Solution if your problem is solved.


I am not an HP Employee!!
Intelligence is God given. Wisdom is the sum of our mistakes!!