I’m working on contract and using a private project. My client wants to access it. Do they need to purchase a license to have access to the project?
No, you don’t need to purchase a license for that.
Publish your project as public and share the link to your client
Download your project and host it on your own web server and give the access to your client
Set a playcanvas account and give the user/pass to your client
The project needs to remain private.
Do they need to access the Editor or just builds of the project?
If the former, yes they do need a license.
If that latter, all builds are publicly accessible.