"Rough Guide" over at Antenocitis Workshop does not cover the interior catwalks and stairs or the external resin bits. This building is from the Forward Base Kickstarter and may have been redesigned when the range was revamped a while back.
First order of business is to identify parts and dry fit everything... and I mean everything! I can't stress this enough.
Here I've found the stringers for the stairs and set them dry into the sockets.
I started by dry fitting all the steps to make sure they didn't need any adjustment and to note the way they fit was supposed to work. From there it was gluing the top step and the bottom step into position and then placing the stringers and Catwalk in position before everything had dried.
A view of the adjusted steps through the regular door.
The other two ladders can be seen here under clamps.