There are two things that are useful to understand about mapping drives to SharePoint Online:
1. SharePoint URLs
If you copy and paste a URL from inside of SharePoint Online, depending on which specific part of the site you're copying it from, you may get some extra stuff in the URL that Cloud Drive Mapper can't interpret. For example, it is common if you're looking at the library homepage that "/Forms/AllItems.aspx" will appear at the end of the URL. In this case, you would need to remove this from the URL. However, we don't auto-sanitise URLs because Cloud Drive Mapper can map drives at multiple levels of SharePoint. So it's important that you understand precisely where you want to target the drives within SharePoint and that you're making sure to remove any redundant URL path information when you paste it into our admin portal.
2. SharePoint permissions
For Cloud Drive Mapper to successfully map a document library within SharePoint Online, users must have permission granted at both the Library-level itself and at the Site-level within which the library resides.