Open the COSMO Alpaca Preview extension from the sidebar and search for the forked BusinessCentralApps repo in the tree
On the project "App" do a right-cick and select "Create container" and enter a name for your new container
While the container is creating, right-click on the repository and select "Clone repository"
Open the directory "/App/Layers/W1/BaseApp" within the cloned repository
In the new window, open the COSMO Alpaca Preview and find your container underneath project
Wait until the container is "healthy". When the container is in "starting" status you can do a right click on the container and select "Show logs" to see what is happening
When the container is healthy, right-click on the container and select "Create launch.json" to setup the connection to the container for development
Right-click on the container and select "Download DLL package"
Right-click on the container and select "Copy password"
Right-click on the container and select "Prepare for base app deployment". This sets the assembly probing paths and increases the version of the base app in app.json
In the meantime the DLLs should have been downloaded via your browser. Extract and move them to the .netpackages directory. Reload VS Code for AL to grab those changes
If you haven't got the newest AL extension and seeing errors you might need to set the runtime in app.json to 12.0
Now you're ready to go. Publish with F5 and enter your username and the generated password you copied earlier the access the webclient.