No option to deactivate saying activation code is wrong, credentials not recognised - HELP?

I have a trial version of eM Client Pro set up today.  I also have an activation code.  When I add the activation code I get an error message.  The instructions I can find online say I need to deactivate the trial before activating the paid verion, but there is no deactivate button, just activate, get license or close.  I am trying to add an email account and have issues that keep saying credentials are not recognised so I thought the full pro version might resolve matters,

Hello Linzi,
there is no need to deactivate DEMO version, once you Activate a license key, it will switch to that version.
However, this error sounds like your credential to your mail account are just inpout incorrectly.
What type of account are you trying to set up?

Regards,
Olivia

Hi Olivia, not sure what you mean so tell me if I’m off track - it is an email account for a company that I have started some part time home work with.  My manager forwarded the email from eM Client with the professional license key and I have copied that accurately.  He also gave me the IMAP/SMPT and port details as well as POP and neither option works.  He tried adding the email account to his own eM Client using the same credentials and it worked so we know those are accurate, it just doesn’t seem to work on my laptop.
Any ideas?
Thanks
Linzi