Where to publish fan fiction
You can publish fan fiction on ChronoSagas for free, and readers read it free. Because the underlying world belongs to someone else, fan fiction cannot carry a payment link or be commercially licensed. Everything else works as it does for original books: chapters, serial releases, ratings and downloads.
What makes fan fiction different
The characters and setting are not yours to sell, so fan fiction stays non-commercial. That is the only difference in how it is published.
Writing in someone else's world on ChronoSagas
Authors on ChronoSagas can also allow spinoff books set in their own worlds. That permission is off by default; when an author turns it on, others can publish their own books in that world.
Questions
Can I charge for fan fiction?
No. Fan fiction cannot carry a payment link or a commercial licence.
Is fan fiction free to publish?
Yes, always.