In order to complete this trophy you will need to participate in Online Casual or Competitive matches, as goals scored and assists made in private matches and exhibitions will not count towards this achievement.
This trophy does not retroactively count previous goals and assists scored prior to the update, however the goals and assists will come fairly easily through normal play.
If you would rather do it easier, you can always get a partner to help you boost it in Casual 1v1 matches on the Asia-East Servers as they are not very populated.
You do not need to get both 30 goals and 30 assists, just 30 total between the two.