This from italki Support::
(drop down menu next to your italki profile picture and select Support, then search for skype)
There are two types of Skype accounts:
We recommend that you use a Skype account with a Skype ID because an email address can be linked to multiple accounts, while Skype IDs are unique.
To find your Skype ID on Windows, simply select your profile picture, and your Skype name will be displayed in your profile next to "Signed in as".
So in other words - it works fine with email ID but your email isn't unique so a search might find more than one possible account. If the person you want to talk to has a unique skype ID it might be simplest if you message/call them the first time that way they won't have any confusion about finding you