If you do not upload using drag-and-drop, you can upload customer attribute data via FTP to the Marketing Cloud.
You can upload the data after you create a customer attribute source and an FTP account in the Marketing Cloud. You create one FTP account per attribute source. The uploaded files are stored in the root folder of that account. The data must be in .csv format, with a second .fin file to indicate the upload is complete.
File uploads to the customer attributes FTP site can be done via FTP or SFTP.
To upload the data file via FTP
Ensure that you are logged in to your FTP site at ftp.adobe.com/<sftpname>.
The file type .fin is user-created and signals that the upload is finished. It can be a blank notepad file. For example, if you upload crs123.csv, you also upload crs123.fin.
If the upload is successful, both files are moved to a folder called processed.
See About data file and data sources for customer attributes for important information about file names and structure.