Hello,
phpdocx 7.5 added a new data structure for charts, and your license is phpdocx 7.0. Your script is using the data structure of phpdocx 7.5 that can't be used with phpdocx 7.0.
We recommend you to check the samples included in your package in the examples/addChart folder, or upgrade to phpdocx 7.5 on MY PHPDOCX page if you want to use all features added to the latest release of phpdocx (https://www.phpdocx.com/news/post/phpdocx-v7-5-release-notes/213).
Regards.