To import the data, segment the data, and execute the daily sends as soon as the file is generated by the data lake instance, Northern Trail Outfitters should use a triggered automation that contains an import activity, a series of query activities, and a series of sends. A triggered automation can start when a file is dropped in a specified location, such as an FTP folder. An import activity can import the file into a data extension. A series of query activities can segment the data based on the criteria for different campaigns. A series of sends can send the emails to the segmented data extensions. References:
https://help.salesforce.com/s/articleView?id=sf.mc_as_automation_studio_triggers.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.mc_as_import_activity.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.mc_as_query_activity.htm&type=5https://help.salesforce.com/s/a