The "play simulation" or "bottom slider" missing from the Print Preview screen.
The reason this is missing is because Ultimaker Cura has been unable to detect OpenGL 4.1 support on your computer.
Ensure you have the latest GPU drivers installed from the manufacturer of your computer.
If this step did not fix your issue, unfortunately, this means your computer hardware configuration is not supported for this mode.
Please see here: What are the system requirements for Ultimaker Cura?