In a browser
Try doing the following:
Check that the protection switch on the main screen is on. If it’s not, AdGuard won’t block ads anywhere at all.
Enable Ad blocking. Go to the Protection tab (second icon from the left in the bottom row) and make sure that the Ad blocking switch is on.
Make sure HTTPS filtering is on. Go to the Settings tab (right-most icon in the bottom row) → Filtering → Network and enable HTTPS filtering.
Make sure Base filter is enabled. Go to the Settings tab (right-most icon in the bottom row) → Filtering → Filters → Ad filters and enable AdGuard Base filter.