Elementor Requirements

Please refer this from plugin help docs for details: Elementor Requirements

Requirement Description
PHP 7 or Greater Note: If your site is hosted on a server with an older PHP, you may experience issues. We recommend you ask your hosting provider to upgrade to the latest version of PHP.

Elementor also works with PHP 5.4+, but these older versions have reached official End Of Life and as such may expose your site to security vulnerabilities.

MySQL 5.6 or Greater Another reason is that WordPress also recommends upgrading to version 5.6. So we recommend your host will support PHP version 5.6 or greater and MySQL version 5.6 or greater.
WP Memory Limit WP Memory limit of 64 MB or greater (128 MB or higher is preferred)

For further reading check https://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP.

Browsers Please note that you can use Elementor with Safari, Chrome and Firefox. You will not be able to edit with Microsoft Edge and Microsoft Internet Explorer.

In any case, pages built with Elementor will show up in all the browsers.

Device It is not possible to edit with mobile phones and tablets for the moment. It is possible to work only with desktop computers.
Servers If your website is hosted by WP Engine, you might need to add an SSL to your website to avoid saving issues.

** Credit: As such from plugin help doc page : Elementor Requirements