The name is not enough
A product described as a combination ladder may support several layouts but still not allow stair use. Find the manufacturer’s stair configuration in the manual and check its dimensional limits.
Measure the staircase
Record tread depth, riser height, width, landing size and any turns. Confirm that every foot and support can be positioned exactly as instructed without blocking a necessary escape route.
Avoid improvised levelling
Do not use loose packing, bricks or furniture to lift one side. A dedicated platform or access tower may be better for decorating a stairwell, especially for work needing both hands.
Practise the setup before working
Engage all locking parts and recheck them after each configuration change. If the instructions do not match the staircase, stop and choose another method. Comfort with DIY is not a substitute for a suitable access system.