With Compere running the overall Juggler project, with Medialon Manager running its communications project, and with Marquee running its project on the Source Layout Controller PC, you should see the number of windows available as numbered black buttons in the bottom of the Marquee app.
Note: here, no NDI feeds have been named, but 16 windows have been linked. They are black, so available to be placed. The grey buttons are Window Groups. There are no Presets showing.
In Medialon Manager, you can see the Compere MxM connection in Project > Compere > Variables:
If you already have media directed to the canvas background, you will see this represented in the Marquee background. If not, you will see ‘NDI’. This is what you will also see until you have assigned the NDI feeds in Medialon Manager.
Make sure you can see the Compere canvas panel as well as the Marquee window and the actual display, if possible. In Marquee, press the top left mode button to make sure you see the red pulsing ‘Live’ icon, not the blue-green ‘Preview’ one.
Drag the first of these Windows, numbered 1, into the background canvas area.
As you move and scale this window in Marquee, you should see the corresponding window move around in the Compere Canvas panel, and on the actual display.
If this does not happen straight away, close the Marquee app, close Medialon Manager, then:
•Run Medialon Manager
•Open the Manager project
•Run the Manager project
•Open Marquee
•Run the Marquee project
Test each window in the same way and verify each is working.
You will by now have created a mess of windows, so press the eraser toolbar button on the left to clear the canvas. press ‘Erase’: 
Erase and Remove in Marquee
It is important to understand how the Marquee canvas relates to that in Compere. Traffic is one-way, and window information must remain accessible to Marquee, in order to create, re-add or recall Window presets. Erase means ‘remove all’ rather than ‘remove selected’. ‘Remove’ simply means ‘un-enable’ in Compere:
The Window remains where it was in Compere, but can only be resized or positioned in Compere itself by re-enabling it first. When re-added to the canvas in Marquee, by dragging or enabling a preset, it is re-enabled in Compere.