The screenshots show that you’ve already bought the in-app purchases.
The RoomWorks reverb plug-in shown in the third shot can be unlocked for free, when registering Cubasis (please follow the on-screen instructions).
Please go ahead and try to load the Classic Machines instrument and Waves effect plug-in.
Given the information shown on the screenshot, they should load and work just fine.
How to load Classic Machines
Please tap the piano icon on the MIDI track in the track list
Choose “Classic Machines” from the list
How to load the Waves effects
Please tap the “Insert Effects” tab in the inspector to the left