Apparently on Windows you need to:
Download https://raw.githubusercontent.com/cakephp/phinx/master/bin/phinx.bat and save it in to the vendor\bin folder.
Then run instead
vendor\bin\phinx migrate -c phinx.php
Note also that you should not have the whole CMS source tree inside your htdocs folder. Hopefully you’ve set your webserver web root to be just the web folder inside the Xibo code.
We’ve not tested with PHP 7.3 yet so you may encounter issues in that regard too.