Board Game Arena

I'm completely new to Xeno Invasion and this happened during my game, I don't know why the game doesn't allow me to settle, maybe I've misinterepted the rules.

I have Rebel Cache, New Galactic Order and Anti-Xeno Mitilia for +4 military. I also have Alien Weapon Cache with a good (remove good: +3 military to settle Xeno worlds)
The game doesn't allow me to settle Xeno-Infested Alien Outpost (7 defense Xeno world). I tried to settle by clicking on the good and then the Xeno world card, but game doesn't allow me to settle. Am I doing somthing wrong?

Have you tried clicking the good and then Alien Weapon Cache? That's usually how the BGA RFTG implementation handles "spend stuff to increase military" type cards - you activate the power to get +x military and then choose a card to play from your hand afterwards.