Hello there,
I am pretty certain that we as developers cannot fix this. The ansible directory including the playbook is simply not part of the B2B repository as of now.
The following approach might help you:
Use the standard shopware 6 vagrant box and clone the B2B repository into where the regular shopware installation would be. Then you can bootstrap the B2B suite using the command: ./psh.phar platform:init
I would recommend using this for trial purposes only, since there might be a B2B plugin (as it was for SW5), which should be easier to install.