Hi there, For starters, you need to be 800 power level, which it looks like one of your characters is. Afterwards, you need to do the mission "A Shadow Overhead" on IO. According to your game history, your hunter has done that. After the mission, you need to talk to the Drifter, who will send you to do a contact public event. After completing the event, you go back to the drifter, and decode an umbral engram. Afterwards, you'll be able to decode all umbral engrams you receive. Hope this helps.