How should I handle shipment in E-Commerce development?

Hello,

I'm currently making a custom e-commerce store for a client.

The store is selling electronics. I'm almost done with everything but what about shipment?

I let the user enter their phone numbers & shipment address. Now is it "illegal" or something to let client handle shipment himself if he's fine with it?

Are there any more development required to connect with shipment providers or something?

Thanks!