I am not the salesman, but the 2-row mode ;-)
You are using the 2-row mode instead of the 3-row mode.
Therefore, the vertical space in TM FX is smaller!
If you switch to 3-row mode, you will see the layout presets menu. Then you will also see the ‘Sub’ button.
You can also stay in 2-row mode, but then you have to collapse the ‘Groups’ menu (click on the little triangle).
For a while, I thought it wasn't implemented, but when I saw your screenshot, I remembered that you have to collapse a window to create some vertical space to see any remaining menus.
The problem for you was not being able to see the Layout Presets menu in 2-row mode because the TM FX window stops right at the end of the Groups menu, and you can't see the next one yet.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14