You can always call or text your driver to let them know your exact location. Usually the app will pinpoint your location but messaging them is probably best. For example I get picked up behind Trader Joe's and I let them know I'm behind the building.
The mall is an open air mall that actually encompasses several different blocks. You may find it easiest to find a cornerstone store like Target or Walmart and tell them to meet you there. That or one of the many restaurants disconnected from the mall (Casa De Pico, BJs, Claim Jumpers). That would make it easier for you to get picked up.
If you are in the front of the mall it should send your location. But sending a note to let them know the exact place e you are in feont of could be helpful.
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