To use the LiveMap Viewer option you need to buy it from your panel or during the first order. You can check options here.
After you purchase, you must to create the config of the viewer.
1. Go to the "MAINTENANCE" panel.
2. Choose the "LiveMap Viewer" in the list.
3. Choose your map in the select list, for me it's the "TEST" map.
4. You need to put a name, for me it's "TEST" again. Then select a world feature: normal, nether or end, and day, night or cave.
5. After the configuration click on the "ADD VIEWER" button to create the first config line.
Wait during the generation of the viewer's config file.
6. Click on the URL to see your Viewer map. (You can regenerate the link, it doesn't affect the viewer)
Important the "LiveMap Viewer" can take a long time to generate your map, it depends of the map size.
For me the generation has took 4 hours.
If you don't see your map try to zoom in, sometimes they are small.