EX2 Encryption and Security

I have about 100 GB data on EX2 2TB (in RAID 1). I now need to encrypt the drive (per employer). I see on Page 85 of the EX2 manual, under “CHANGE RAID MODE” I can click on the padlock-icon to change to encrypted mode (still keeping it in RAID 1) I think setting it to Encrypted mode just puts password lock on the drive-access, with no changes to the files themselves. So, if I just click on that padlock icon, will all the files be preserved? Or should I do this after backing up all data to other location and completely emptying the data from the EX2? What happens to the remote-access accounts that I have already set up? Thank you.

encryption is not a password protection, every file will be modified to be read only from a specify user with a specify rights.
That’s mean that if you mount one of 2 HDD to another NAS/USB the data will not be read
It shouldn’t delete all your files but, to be secure, make a copy of them