To check how long the file delivery link is available for the client, open Configurations > Projects and Quotes > Settings > Workflows (Classic) tab > Files Available for Client via FTP/HTTP for (days):
Click on the Edit button to set another period.
If the link for the client is expired, it cannot be regenerated. In this case, the files should be sent to the client outside of XTRF if the client doesn’t use the Client Portal.
It’s worth mentioning that all files can be downloaded at any time directly from the Client Portal.
Ref.