With the two default adlists, you should not see many ads. YouTube and Facebook are exceptions. These tolls can help you determine the source of the ads:
You will want to ensure the client on which you are seeing the ads is using Pi-hole for DNS.
From a client that you believe should be connected to the Pi-Hole for DNS, from the command prompt or terminal on that client (and not via ssh or Putty to the Pi), what is the output of
nslookup pi.hole
Also, please post the token generated by
pihole -d
or do it through the Web interface:
Tools > Generate Debug Log