Ownership/permission problem with automounting exfat drive

I'm new to Linux and am having problems automounting an exFat-formatted partition on a Lacie-disk in Ubuntu 16.04.

I installed exfat-fuse and exfat-utils and could then mount manually using:

sudo mount -t exfat /dev/sdb2 /media/maria/Lexfat

The exfat disk would not automount, however, so I edited /etc/fstab (not sure what the options mean, though, so perhaps the problem is there...?):

sudo nano /etc/fstab/dev/sdb2 /media/maria/Lexfat exfat defaults,auto,umask=000,users,rw 0 0

(I tried to get an UUID using blkid, but this does not list my exfat disk)

Now, the disk is automounted when I startup Ubuntu, but owned by root user.

So I need to give password to unmount it and am not allowed to remount with GUI. I am not allowed to change ownership using chown, either.

I have transferred files from a remote server to the disk using rsync, which works fine except that I get

failed to set times-error

I'm guessing that both the mounting and rsync issues are ownership/permission problems, but I don't understand how to fix it. Any ideas, please?