I do not have Geforce Experience installed and I believe it is not required for Ansel. I do have the Game Ready driver 460.89 installed and Ansel pops up on the left side of the screen when Alt F2 is presses and disappears on Alt F2 or Esc.
I run Windows 10 Pro.
Geforce Experience is required for Nvidia video recording (Alt F9).
Ansel is not compatible with older Nvidia cards
https://www.finder.com.au/nvidia-ansel
Scroll down to see the compatible card list.