Addendum
After installing the regular version MM2024.2.1.3201, I noticed that MonkeyMote also works for the debug version.
Therefore, I performed further tests on a second notebook.
In a first step, the portable debug version MM2024.2.1.3201 was installed. In addition, the MonkeyMote add-on (1.8.

was added. Result: no MonkeyMote icon in the taskbar.
In a second step, the non-portable regular version MM2024.2.1.3201 was installed in addition to the portable debug version. The MonkeyMote add-on was also added to this regular version. Result: MonkeyMote icon present in the taskbar. The iPhone app MonkeyMote runs as expected.
Finally, I uninstalled the non-portable regular version and installed the non-portable debug version including the MonkeyMote add-on instead. The result was that no MonkeyMote icon was displayed.
This means that in order to use MonkeyMote, you need to install a non-portable regular version of MM.
My problem with MonkeyMote in the past was that I was running MM in portable mode.