Hello Vaibhav
Regarding the 500 server error that you are getting, could you please check the points in the documentation link below:
https://www.joomshaper.com/documentation/sp-page-builder/sp-page-builder-2-x/500-internal-server-error
First read the common cause of Internal Server Error 500
If you have JCE Editor, please upgrade it to the latest version, clear the browser and Joomla cache and try again.
The php.ini file might set to only having 32 Mb memory. Changing it to 128 Mb can do the trick. If you are a Windows user, the path to file is /xampp/php/php.ini and is a MAC user, then /private/etc/php.ini.