Protonmail IMAP works but not SMTP

Greetings!

Former Postbox user here, currently on the 30 day trial for eM client.

However I have a problem with setting up Protonmail SMTP. Yes, I am on the Mail plus plan, so I can use eMail clients and also have bridge installed. IMAP sync works fine but somehow I cannot send eMail via SMTP. I’ve used the exact settings from Bridge and also followed the steps from this thread:

As mentioned, while SMTP does not sync at all, IMAP works just fine so I am ruling out an issue with PM Bridge. Attached is the error message I am getting.

Any help would be appreciated…
Many thanks!