I am having trouble activating the free license

I am using eM Client Version 8.2.1478 (856f724)
iMac 24inch (early 2008)
OSX El Capitan Version 10.11.6

Demo has expired, I acquired a free license to use eM Client for email. I copy and paste the activation code and get an error stating " A problem has occurred when contacting the licensing server:
ActivateLicenseFromApplicationEx failed "


I have no fire walls active on this imac.
If I did have a firewall, what port(s) would need opened if that is the issue, so the server can activate this license?
I can look into the gateway router’s settings maybe.

I really need this to work.
Thanks in advance.

eM Activation Error