Soundiiz is supporting the import of Musi (iOS) playlists to other streaming services with the Share link provided by Musi (feelthemusi) in the app itself.
For that, go to your playlist on Musi (iOS) and use "Share" button to get an URL using "Copy Link".
The URL should like, for example: https://feelthemusi.com/playlist/snups1
Then simply go back to Soundiiz, tab Playlists and use the "Import playlist" button in the top right of the interface and select "By URL". Then paste your URL and follow the steps!