1/ Check this article – https://codeless.co/slider-revolution-ajax-error/
2/ Contact your hosting provider and ask for help, maybe information from the server error log will point you in the right direction what needs to be fixed.
3/ Try to disable all the third-party plugins (including cache plugins), that do not come bundled with XStore https://xstore.helpscoutdocs.com/article/36-included-plugins , clear cache of browser, and check then. Maybe one of the additional plugins is a reason for the problem.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.