1. PHP REQUIREMENT LINK : https://github.com/freescout-helpdesk/freescout#requirements
2. Select (GMT-04:00) Eastern Time (US) in manual installation.
3. Before running manual installation add APP_TRUSTED_HOSTS ='[[domain_name]]' in blank .env file , or else it gives error 
Access denied Untrusted Host: [[domain_name]]. Add the following to your .env file and clear cache: APP_TRUSTED_HOSTS ='[[domain_name]]'
4. set date.timezone = "America/New_York" in php.ini before manual installation and set the same in cache/config.php, .env and in sql  if there is any change in timezone.
5. Upgrade added since 1.8.194, We use the manual method to perform upgrade as mentioned here in their wiki https://github.com/freescout-help-desk/freescout/wiki/Updating-FreeScout#method-5-update-manually