ClassLink will provide you with a dedicated username and password in order to upload your OneRoster files via SFTP.
SFTP OneRoster CSV files
Using an STFP program like WinSCP (https://winscp.net/eng/download.php) or FileZilla (https://filezilla-project.org/download.php?type=client), login with the server host information and credentials provided by ClassLink.
Once connected, drop the OneRoster csv files in the DailyImport folder, as shown below.
Now that the files have been uploaded, they will be imported during the set import schedule (found in Settings) or by manually clicking the import button below. To initiate the import, go to the IMPORT ROSTERS module and click on Import Now.
After your data has been imported, scroll down to view a summary report of the import.
The report will provide information on records added (in green), removed (in red), as well as deltas (the orange triangle), errors and warnings. If data has an error (for example, a user has no givenName in the CSV) then it will not be imported, and an error message describing why will be given in the summary. Data with a warning will be imported, but a warning will be given in the summary. Deltas are data that exists on the server that was changed on a subsequent import (for example, a class period was changed from one import to the next).