Make sure that HTTPS filtering is enabled. To do so, press AdGuard icon on the menu bar → Settings icon ⚙ → Preferences... → Network → Filter HTTPS protocol.
In the same "Network" section, there should be a tick next to "Automatically filter applications". Check that your browser is on the list. Open the Apps tab and check that your browser is on the list.
Open AdGuard Preferences... → Filters and turn on AdGuard Base filter and Language specific filters for your particular language. Then click Check for filter updates.