You have two options.
First, you can wait for a ROUTE # 21 TAGBAK – FESTIVE WALK TRANSPORT HUB VIA SM CITY/ATRIA at the main entrance of the mall. This will take you to Tagbak Terminal. But please note that this could take a longer wait time.
Second, if you are able to cross the overpass, at the SM Strata parking, you can ride FIRST TOWN ILOILO: LEGANES DIVERSION JEEPNEY ROUTE. This will also take you to Tagbak Terminal.