In the last battle for Fort Condor, you are able to get the Phoenix summon materia and a Huge materia. Do you have to actually win the Fort Condor mini-game to get these? Or, if you fail the mini-game but still defeat the boss triggered by failing, do you still get them?
The short answer is No, you can obtain the materia by other means outside of Fort Condor. As far as winning it at Fort Condor, you can lose the mini-game, but must defeat the boss (CMD. Grandhorn) at the end of it.
CAUTION: May contain spoilers for those wishing to figure this out on their own.
From the Wiki:
Phoenix Materia is obtained at Fort Condor if Cid and the party manage to protect the Huge Materia inside from Shinra. If they do so, the Condor sitting atop the fort dies and its baby hatches. During the condor's death the fiery wings of a Phoenix are seen, and afterwards a Phoenix Materia can be found lying on the floor near the nest.
If the player loses to the boss fought atop Fort Condor after failing the minigame to protect the fort, they will not obtain Phoenix, but it can still be dug from Bone Village after the event.
If you miss out on the Phoenix materia at Fort Condor, here is how you can obtain it:
You can obtain it by digging at Bone Village from Location 4 on the map below.
More details can be found about Bone Village on the FF7 wiki.