For better performance (and better security) we obviously recommend the version 7.4 or greater for PHP. Nevertheless, if this is not possible for you (server type, incompatibilities with plugins, etc.) we recommend at least version 5.6.X.
Finally, this topic might also catch your attention as one of our user shared the server configuration that has helped him to solve a similar issue:
You're trying to setup your theme but you're experiencing errors when importing the demo content? Or you've just followed the setup guide but your website doesn't look exactly like our demo? These are common issues for which you can find easy and quick fixes.
Feel free to review our theme on Themeforest! It helps us making our products more known to new potential customers, which allow us more time to improve the quality and develop new features. #SharingIsCaring ❤️