Issues by the “Destination” block

Button Test creates empty files on FTP server

It’s a FTP server limitation. You  should edit the job and mark “Passive mode” at tab “FTP”.

I don’t receive emails with attachments

1.  If you use XLS format  – open section “Email”, checkbox “Append file contents to email body” must be turned OFF.

2.  Some mail servers can require additional verification for  emails  with attachments.

So you should use SMTP plugin, like

How to append records to existing CSV file (at FTP server)

You must turn on option “Append to existing file” in section “FTP settings” (inside the job). The plugin will download existing file and pass it to “hook” function. So you have to add following PHP code to section “Misc Settings” (inside the job too!). Probably you should tweak this code a bit.

I send order as json to API endpoint, but API doesn’t see data

Probably, API waits for HTTP header. Add following code to “Misc Settings” and test again.