You can't as of right now but you can make it smaller using this magisk module. It also has a couple other features you may like.
I clicked on setup later,
I also encountered the SD card problem. Samsung 64Gb formatted as exFAT. The phone says it's corrupted. The card works fine in other phones and on PC.Thanks for the latest update!
I don't know if this is a bug or it is just me, but 4.6 won't mount SDCards with exFAT default file system anymore, it will force you to format the card according to system's default (FAT32) before you can mount.
I have 128gb sdcard and it supposed to mount without "format" prompt when I was using 4.5.
i had the same problem, SD card prompted me to format it. restarting solved it. no problems so far. 16gb no-name brand. Upgraded from HavocOS 3.9