Legacy Mode was required to run EZCA in Prepar3D v1.4. It's not required to keep EMT running in order to run EZCA in Prepar3D v2. You should be running the latest EMT update. It will give you the options to sync Virtual FSX for FSX, Prepar3D v1 or v2.
1) EZCA installs to Program Files (x86) automatically without the use of EMT. The final updated version of EZCA 1.17 contains some of the code that EZCA 1.17 beta used for Prepar3D v1. You don't use the beta version of EZCA for Prepar3D v2. Just use the 1.17 final updated version.
2) Once EZCA is installed, you must have the EZCA entry listed in the exe.xml file. EMT, when first installed, created the exe.xml file. You just have to manually add EZCA as noted in other posts.
3) You now run EMT and "Enable Virtual FSX", but don't start Prepar3D v2 yet. Don't be concered with "legacy mode".
4) Go to EZCA and start EZCA config.exe. Tick the "FSX" button and the "201 camera" file entry will be added to all airplanes and rotorcraft aircraft.cfg files you have installed. You close EZCA config.exe when "success" has finished.
5) You can now disable EMT "Virtual FSX" and close EMT.
6) When Prepar3D v2 has opened, you can go to Addons in the Options header and start EZCA from the pulldown menu or pause the sim and start EZCA manually.
IF successful, the only time you need to run EMT along with EZCA config.exe is when you've added new aircraft (see #4).
That's all of 5 cents I've got to give.
plug_nickel