The package which you installed from Themeforest is a single click install package (themeforest-5901345-rock4life-joomla-template-for-bandsmusicians.zip). There are 6 component and 1 template zip file in it. You can install it directly as a single extention or you can install each zip file one by one.
To upload one click install package, your server should allow clients to upload minimum 10 mb. If you are getting an internal server error during the installation, you should contact your hosting provider.
Where is the help documentation file?
Unzip the main file. Open “Packages” folder. You will see new zip files. Unzip “tpl_rock4life-1.0.0.zip file. Open rock4life-joomla -> documentation folder and click on index.html file.
You can also access to the help documentation via Joomla Admin Panel;