I have performed many SharePoint on-premises to SharePoint online migrations. but i have a project to do a migration from drop-box to sharepoint online. now i read about drop-box and seems it is a personal cloud storage, where users upload and share files. so when i want to plan a drop-box to SharePoint migration, is this done on user-basis ? for example we need to migrate each drop-box storage to the user's one-drive or to a separate site? or inside drop-box we can access all the files and folders for all users from a single place, so we can migrate them to a single site at once?