Need help installing full Kali Linux (not live) to USB flash drive

Hey all,

this is my first post, glad to be apart of the community :). I am having trouble installing a full encrypted version (not live or persistent) of Kali Linux to my 16gb flash drive. Everything goes fine until I get to the step where I'm asked to install a bootloader. Both options fail. I tried finishing the installation and using SuperGrub2 Disk to install grub that way, and that doesn't work either. I see no reason why installing a full version of Kali to a flash drive can't be possible. I'm attempting to install from a Live Cd btw.

Any ideas on why this isn't working? I'm attempting to install the 64-bit version, and the computer I'm working is a 64-bit AMD (Toshiba Satellite).