Don't remember the quest off the top of my head but read some of the fine print in the Quest list. Curiosity searching typically needs either JUST a probe ship, or a set of resources or a Hero of X level. I think there was one other weird one but digging into the actual quest entry will typically hint at what you are missing. Lastly, you can NEVER use the system build queue to activate these curiosities.

Originally posted by Jim Garry:

But it always tells me "Your fleet doesn't fill the quest requierements"

There's also the “expedition level”, as you learn the technology, the probes become more “advanced”
If you explore (receive in exchange) technology "Baryonic Shielding", you'll get "Advanced Scanners"

Originally posted by endless-space-2.fandom.com/wiki:

• Sets the Curiosity Detection Level to 3
  
• Sets the Curiosity Expedition Power to 2