There's multiple ways to start a convert process on Soundiiz interface.
Using Transfer tool
As a Free user, we are recommending you to use the Transfer tool, an easy and fast solution.
- Select Transfer under Tools
- Select a Category (Playlists, Tracks, Artists, Albums)
- Check elements you want to transfer
- Select the Destination platform
Using Platform to Platform tool
As a Premium subscriber, you can use the Platform to Platform tool to be able to transfer all your datas in one time and leave it running in background !
- Select Platform to Platform under Tools
- Select the Source platform
- Select the Destination service
- Check Categories (Playlists, Tracks, Artists, Albums)
- Use Select items to check elements
- Confirm your selection to transfer
Using Your Library lists
You can also at any time do a right click or three dots 
and select Convert to feature to transfer any kind of element (Playlist, Track, Artist or Album) between music platforms.