64-bit operating systems
ETS5 is a native 64-bit application. The advantage 64-bit applications is that they can address more RAM than 32-bit applications.
ETS3 & ETS4 device plug-ins
ETS3 & ETS4 device plug-ins are only available as 32-bit software and can therefore be the reason to put ETS5 in 32-bit compatibility mode.
Compatibility Mode app
ETS5 can be put in 32-bit compatibility mode by means of the 'Compatibility Mode' app. This app is upon ETS5 installation installed and licensed, but needs to be activated explicitly.
It is recommended to only activate this app when really necessary, because activating it means that ETS will work as 32-bit software instead of 64-bit.
Apps can be actived/deactived via the 'Apps' list at the right side of the ETS status bar.