MailJet Configuration with UNA 14.0.0

I have MailJet set up including Domain, SPF, and DKIM validated. I have installed the latest version of SMTP app/module on UNA and configured it in accordance with @Chris 's tutorial. When I test the SMTP with all of the combinations of port numbers (25, 443, 465, 587) and security protocols (none, SSL, and TLS), I continue to get a connection error in the bx_smtp_mailer.log. I am using my API key and secret key as my username and password respectively and I have the mailjet subdomain added in accordance with their instructions. Has anyone struggled with connecting like this? Seems like I'm missing something simple. I've looked through all of the results by searching UNA with "mailjet" in the search bar, but nothing jumped out that I haven't tried.

Any help is appreciated.

UPDATE: I have recently updated to 14.0.0 and changed the title of this post. Yet, the problem persists.