Incorrect login details used:
Login details used by users for FTP access include their username and password. If these credentials are given wrongly in the FTP client, it can result in a 530 login error in FTP.
"530 Login authentication failed" errors also happen due to wrong password. Even a single additional space at the beginning or the back of a password can cause a login failure.
Path doesn't exist:
When the FTP users is created, a path will be assigned on creation. If the path doesn't exist on the server, this will cause a login failure.
No TLS used:
TLS is required and enforced for security reasons. It's a very bad idea to disable it, since passwords would be sent in plaintext. Make sure to activate "Explicit SSL/TLS" in your FTP client. However, if you need to disable SSL anyway (For example incompatible ERP system that only supports plain text FTP), you can do so here:
, you can do so here: