The plugin requires some points to get it run smoothly, make sure your hosting and Wordpress version are satisfied the requirements.
- PHP Version: 5.6 or higher
- Wordpress Version: 4.0 or higher
Ultimate Media On The Cloud required to work without other plugins with same functionally (Cloud Media Upload, etc...), if you have other plugins with doing same thing, please DE-ACTIVE them in order to get Ultimate Media On The Cloud working properly.
If your hosting and Wordpress source are not meet the minimum requirements above, in case you have to upgrade PHP version and Wordpress version first before installing plugin and moving forward.