The Take 1 (https://vitac.com/take-1/) company providing the caption service will provide you with the ftp credentials that will be required in order to set the publishing button up.
Please follow the instructions below to create the publishing button:

Settings
The FTP server address is typically set to: secure.take1.tv
Username will be provided by Take 1 once the account is opened with them

Source:

Formats:
Add the H.264 and EDL output formats

H.264

Single EDL

Roles
Once ready enable the button for chosen roles