1. PHP REQUIREMENT LINK : https://github.com/freescout-helpdesk/freescout#requirements
2. Select (GMT-04:00) Eastern Time (US) in manual installation.
3. Always create blank .env file and give permissions before hitting installation URL , as script links redirect to root URL , even if its adjusted in .env, which installer creates.
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