A:Answer It's a native 32:9 display, the equivalent of having two 1920x1080 HD displays side by side.
If you're talking maximized windows based on a native 16:9 1080 display the most appropriate answer to your question could be 2 windows but your description is unclear as the "number of windows" depends on the resolution of a monitor *and* the sizes of the windows.
This monitor, besides being a single 32:9 native display, has 3 separate inputs and a PBP mode that can run it (using 2 inputs) as two 1080 16:9 displays or (using 3 inputs) three lower resolution (not 16:9) displays or a non 16:9 1/3-2/3 (or 2/3-1/3) split (using 2 inputs) versus the normal single display 32:9 native resolution default.
Note that your Intel Graphics via HDMI may or may not be able to run the native single input 32:9 resolution of this monitor and the monitor does not have any USB-C inputs.
if the Intel Graphics of your T15 won't do the full 32:9 native resolution of this monitor you could probably come up with a USB-C device for getting the T15 to do more than one external monitor output and run this monitor in dual-inputs PBP mode.
