Not able to use the plugin

Dear Support,
I installed the plugin and tried to use it for integrating with Amazon sales channel.
However after installing the plugin whenever i tried to go to settings or any other option of the plugin it prompted for log in as my Admin. When i logged in as Admin another window got opened inside the wordpress panel. When i again tried to use any option of the plugin similar log in pop up opened again. Tried other option to check but whenever i tried to use any option only log in pop opens.

Have i made any mistake in using the plugin.

Best Regards

The page I need help with: [log in to see the link]