You have not said what happens if you enter details on the first screenshot and continue. Do you get an error? Other options?
I can't speak for Geary itself but some email clients hide the advanced options. For example some clients would consult a database of known email servers to find what the parameters should be or they may ask for the basics as per your first screenshot., then the client will attempt to connect to the email server, first say using no encryption, if that does not work it may try again using SSL, if that does not work it may try again using SSL/TLS etc etc until it either finds a set of encryption/port parameters that works or if it can't find anything that works it will likely prompt for custom advanced parameters. That way for the majority of users it will "just work" without them having to know or input all the exact parameters.