Here’s good link for downloading the route and also, for planning accommodation.
Under ‘Plan a trip’ select camping and it will display campsites along the way.
In short, you will find many campsites along the route.
https://cycle.travel/route/summary/162515
In this example near Morlaix, there is a green tent sign (circled). Zoom in and click on the green tent and it will give you the name of the site.