Buy a book, subscribe to a podcast, or find a local teacher.

The italki message interface is pretty awful. It's usable to make contact, but not for much else. I read your profile: How can you learn online without some sort of voice communication? I can understand not wanting to use social networks, but many of what you listed are messaging apps, not social media. As Joe said - if you don't want to use messaging apps, your online learning options are limited. Use passive learning, or go back to traditional learning.