What resolution should I create my Ctrl Suite interface?

Create your Ctrl Suite interface resolution for the same resolution as the device you intend to view it on.

Note that this resolution of the display may not be the same as the operating system uses.

Factor in display scaling on Windows and macOS.

For iPad and iOS devices there's a good reference tool at https://www.ios-resolution.com/ which details the “logical size” for each device, remember to use the logical size and allow for a margin for the best result.

If you have access to the device ahead of your installation, install and open Ctrl Player on it in full-screen mode. This will display the resolution that Ctrl Player is operating in.