Magento 2 Professional Developer certification study guidelines
You can still take the practice test here: https://swiftotter.com/technical/certifications/magento-2-certified-developer-practice-test#/
The basic version is free, you can choose to pay for better / more questions.
As for a copy of the study guide - why do you not simply pay them for their work? They even refund you if you fail.
The "swiftotter" site now not provides the free study guides.Please refer the following reference link for preparation.It is best.
https://github.com/magento-notes/magento2-exam-notes