If you get su: Sorry for normal user account under FreeBSD implies you are a normal user and cannot switch to root. To enable the current user to switch to root by su command the user must be a member of the group wheel.

We can add the user account to the wheel group by:

pw user mod username -G wheel

Example:

pw user mod Alice -G wheel

You need to be root or have sufficient privileges to add a user to the group.