Let me brief you what is this error about and then explain the restriction with the download.
What is user Purge? Once the user is soft deleted (deleted manually from the admin users section or removed the user in the user CSV file), the user will be in the “User Cleanup” section (below is the screenshot for reference) i.e., the user will lose the access to the account but data associated with users are still available in ALM.
However, if the admin manually chooses Action > Purge user, the records associated with users are completely erased after the purge process.
Issue with downloading from import logs: If a user has been purged from the account, the CSV is removed so that the user’s data is erased from the system. The CSV may not be recoverable directly from import logs. Suppose you require a list of all the users in the system. In that case, this information can be downloaded from the Export User data field in the Users > Internal tab (this is not the exact CSV imported via FTP/others but will contain all users’ data).