Along the southern end of the barracks in the Resistance Base you’ll find the Datapad "Report: Estraaja". Read it to start the quest "Intercepted", whereupon you decide to investigate these missing supplies. Make your way northeast to the command center to find Olisk, who initially tries lying before eventually coming clean. Offer to help out and he’ll direct you to pull the navpoint to the drop point from his console… you know, if you want to go on this unsanctioned witch hunt on your own. Continue northeast and interact with his Console to get the navpoint, which isn’t too far north of the Resistance Base.
Note: There are two other consoles in the command center of the Resistance Base that you can access to start this quest.
From the first Forward Station (just east of the Resistance Base) simply drive north past a Mining Zone towards the navpoint you scoured from Olisk’s console. At the navpoint you’ll find the missing supplies - and the reason why they’ve been going missing. Put down these hostile Angara, these Roekaar, which consist of Roekaar Raiders (simple gun-armed foes) and Roekaar Sharpshooters (shielded, armed with a powerful sniper rifle) then read a Datapad "Urgent Message" to learn that somebody named "Akksul" has been robbing the Resistance. Ah, internal Angaran politics. For this task you’ll earn 270 XP, 29 AVP and +2% Voeld viability.