Completing A Symbol of Unification might be one of the most rewarding quests in Arc Raiders, relative to how much time it actually takes. The entire mission consists of two small tasks: finding a flag in a Raider outpost, and hoisting said flag above said outpost. Doing this gets you the Aviator outfit (that one with the headphones), so it's well worth the time.
In this quest, Celeste asks you to head to the Formicai Outpost on Dam Battlegrounds to do your flag waving. Finding the flag is pretty straightforward, but you might be struggling with where to hoist it. Either way, I'll run through the whole A Symbol of Unification quest below.
Since you're not extracting anything, it might be worth bringing a free loadout, especially as the trek to Formicai can be quite long if you get an inconvenient spawn.
Locate the flag at the Formicai Outpost
First off, head to Formicai Outpost in the south of Dam Battlegrounds, on the rocky mound to the south, above the Scrap Yard. The easiest way to get inside is to follow the trail up the hill that leads around to its southern end, where you'll find the entrance.
Just as you enter, look to your right for a medical gurney with a yellow-marked backpack on it. Interact with this to get the Raider Flag item.
Hoist the flag on the small platform overlooking the Red Lake
Now, you need to raise the flag above the outpost. Continue through into the main cylindrical room and go straight ahead out onto the exterior northeast balcony overlooking Red Lake. On the left side of this platform, you'll find a pole you can interact with to hoist the flag.
That's it, quest done! Head back to Celeste to get your reward, including the Aviator outfit.
