Only upload over ftp possible, no sync?

I've owned a license for Hazel, but over time I had no need for it anymore.
Until I upgraded to Catalina, as it appears it is no longer possible to use SMBv1 to access network folders. I use this connection to access a USB drive that acts as a buffer between macOS and a network scanner. There is no route toward other parts of the network, so either SMBv1 or ftp are not really a safety problem in this case.
macOS Catalina --- ftp --- file server --- USB drive (read/write) <-- scanner
Sadly macOS only let's me mount an ftp share as read-only for some reason. I was pleasantly surprised however to learn Hazel has a built-in ftp client, with which I can indeed upload and download files to the USB drive. But that appears to be it.
This is a partial solution, as the drive will now slowly fill up with files, which is undesirable. Isn't there a way to sync folders over ftp, i.e. also delete files over ftp?
To be clear: I am limited to SMBv1 or ftp with these devices and don't want to open SMB ports on macOS.
Until I upgraded to Catalina, as it appears it is no longer possible to use SMBv1 to access network folders. I use this connection to access a USB drive that acts as a buffer between macOS and a network scanner. There is no route toward other parts of the network, so either SMBv1 or ftp are not really a safety problem in this case.
macOS Catalina --- ftp --- file server --- USB drive (read/write) <-- scanner
Sadly macOS only let's me mount an ftp share as read-only for some reason. I was pleasantly surprised however to learn Hazel has a built-in ftp client, with which I can indeed upload and download files to the USB drive. But that appears to be it.
This is a partial solution, as the drive will now slowly fill up with files, which is undesirable. Isn't there a way to sync folders over ftp, i.e. also delete files over ftp?
To be clear: I am limited to SMBv1 or ftp with these devices and don't want to open SMB ports on macOS.