You can check your progress by pressing start and scrolling down to where you're on "System". Two above this is "Bridge Links". Click on this, then click your name (should be auto selected), and then tab over to where it says "Structures" on the right. In the top left portion of this, it tells you everything you've done.
Due to the nature of order 46 (for cargo catapault) being tied to Episode 5 (this order is the conclusion of the episode), the soonest you can get this achievement is Episode 5. You will unlock PCC level 2 after reaching level 1 with the weather station.
These structures are built in the course of mandatory story missions:
- Postbox
- Watchtower
- Safe house
Can do at anytime:
- Sign
Automatically in cargo for story or can be fabricated:
- Ladder
- Anchor/rope
Left to build from PCC level 1:
- Bridge
- Generator
And from PCC level 2:
- Zipline
- Timefall Shelter
- Cargo Catapault (unlocked after Order 46, a story mission given soon after reaching Mountain Knot City)
- Chiral Bridge (Order 81 from the Chiral Artist)
- Jump Ramp (Order 80 from Weather Station)