Thanks for sharing your issue. I am here to fix it. First of all, fix these errors for localhost.
You are getting errors on the localhost xampp server to installing slider revolution and importing demo content. You can remove these errors from the wp-config.php file.
Follow the steps ( localhost)-
1. First of all, go to C:\xampp\htdocs\wordpress path.
2. Find out the wp-config.php file
3. Edit with notepad.
3. Now find out the code - define( 'WP_DEBUG', true );
You need to disable the WP_Debug. To disable the WP_debug, change true to false.
define( 'WP_DEBUG', true ); to define( 'WP_DEBUG', false );
Save your file. And try to install the theme. If the same error will occur then delete all theme data from PHPMyAdmin and install again. It will be removed.
Steps for Live server -
1. First of all, go to your public_html folder. This is known as the root folder of the website.
2. Find the wp-confg.php file for your WordPress website.
3. Edit wp-config.php file with live server editor.
4. Disable the WP_Debug. Find out the code - define( 'WP_DEBUG', true );
5. Change define( 'WP_DEBUG', true ); to define( 'WP_DEBUG', false );
For enable WP_Debug, define( 'WP_DEBUG', true );
for disalbe define WP_Debug define( 'WP_DEBUG', false );
You have to disble WP_debug and save the file .
It will be helpful for you. If the problem does not fix, please comment to me.