[cypher]

Although some robos will climb (usually when you don't want them to!) climbing isn't natural for them & with furry feet they can slip easily.
What kind of ladder do you have?
If it's a rough wood like a bendy bridge, not open runged, & not too steep some robos may manage but if yours isn't inclined to climb then I wouldn't try to encourage it due to the risk of falls.
Maybe just make the substrate deeper in part of the cage if you can so he can burrow more naturally.