In case, you do not have Thunderbird installed, this guide will be very helpful:
https://webhostface.com/kb/how-to-install-thunderbird-on-my-windows/
Once you have Thunderbird installed and running, click the File tab -> New -> Existing Email Account…
Type in your Name, Email Address and Password.
Hit Continue, Thunderbird will automatically detect the server settings and then click -> Done.
After that Thunderbird will ask you to confirm the server Certificate.