This seems like a part about specifically being an LSP to private, mobile nodes using the Dunder LSP spec.
To become an LSP that uses public channels, you can simply post an offer on Magma. The form will answer the questions about what fees you will charge. Once you've completed a couple orders in a timely fashion, you'll earn reputation and be recommended more often to buyers.
This is a competitive market, so aggressive pricing may be necessary to complete your first orders and earn reputation.