Install the official Shopware 6 PWA plugin. This is a required plugin with useful API endpoints to make hubble PWA work with Shopware
After you successfully installed Shopware 6. Go to your Shopware 6 admin and create an integration, so your PWA can communicate with your Shop programmatically. This is required if you want to install some Shopware 6 Plugins and make them work with hubble PWA.
Last step is to get your Shopware 6 API credentials. You need those credentials to connect your hubble PWA to the correct Shopware 6 Sales-channel.