A common issue that can occur with users new to installing WordPress themes is a “Broken theme and/or stylesheets missing” error message being displayed when trying to upload or activate the theme. This error message does not mean that the theme you have purchased is broken, it simply means it has been uploaded incorrectly. Luckily, there is a very easy fix.

To prevent the installation of outdated, malfunctioning or incompatible plugins, we prevent the installation of old versions.
If you see this error while installing them, please update your theme, and the problem will be solved.

If your theme has a non stop music player, as Kentha, OnAir2 or Vice, please be aware that when logged as admin, Ajax Page Loading is disabled, to allow a safer and easier page editing.

The support covers answers and help within the standard product usage, contents creation, installation, updates and settings.
If you want to do anything not described in the product features or documentation, as changing the appearance or behavior for existing elements, templates or shortcodes, out of the item’s customization possibilities, your request is not covered by the product support policy.

https://themeforest.net/page/item_support_policy

Most of the installation or activation issues are caused by cheap hosting providers that don’t meet the system requirements because of their processing limitations. Before asking support, please be sure your hosting meets them.
System requirements https://www.qantumthemes.com/helpdesk/system-requirements-for-wordpress-themes/