I don't want to back up, just lock the drive

I thought I was just installing password protectioni on my Passport SE, but when I plug it in, the virtual CD mounts, and the software wastes time profiling my Macbook Air and itself. Since this is an old, feeble Macbook, this takes time.

Is there a way for me not to have to deal with the CD and the scanning process, yet keep the password access feature? That’s all I want - a drive you plug in, type in the password, and are ready to go. I’m fine backing up with Time Machine.