If the library is not in the list, it has not been installed.
1/ You downloaded the libraries… correct.
2/ You moved the libraries to personal library folders… correct.
3/ You used the “folder” icon with the pop-up “add existing library to table”… incorrect. This is for adding an already recognized, and translated to kicad, library. This icon is used to re-instate a library that has been deleted with the Rubbish bin icon.
You now need to click on the “+” icon (to the left of the folder icon) , then
Click on the grey space in the library path column,
Click on the folder icon at the right of that line that has now appeared,
Use the page that has now appeared to navigate to the personal library in which you placed the Digikey library.
Double click on that library.
Give the library a nickname and save.
You will need to follow the above same procedure with your footprint library.
Library installation and manipulation is all explained in the FAQ
https://forum.kicad.info/t/kicad-7-beginners-guide-to-personal-symbol-and-footprint-libraries/38738
Edit: Make sure you read the section on “Nicknames” as this determines where, in the library list in the Schematic/Symbol/PCB/Footprint Editors, your Digikey libraries show.