ApeksOPS stores inventory quantities on hand separately from the WooCommerce inventory levels but synchronizes them in real-time.  When you click on the ApeksOPS menu for the first time, all inventory levels are loaded into ApeksOPS automatically.  You don’t need to do anything extra.

If, for any reason, you need to manually synchronize at any point, go to ApeksOPS > Settings > Utilities and click “Sync Inventory Levels”.