How to give Transmission permissions to write on external HD on Raspbian Raspberry Pi media server?

I've installed Transmission on my Raspberry Pi with Raspbian on. Want to download torrents (legally of course) to an external hard drive. Permission is denied. root is owner and group for the drive I've tried to change permissions on the drive following a lot of different instructions here and other forums but can't make it. Found some information on that it's impossible to change permissions on a disk with exFAT. What workaround could I do? My main user is "pi" and I think that's the one Transmission uses. **EDIT: Add content to fstab**

proc            /proc           proc    defaults          0 0
PARTUUID=50913804-01  /boot/firmware  vfat    defaults    0 2
PARTUUID=50913804-02  /               ext4    defaults,noatime  0 1
# a swapfile is not a swap partition, no line here
# use  dphys-swapfile swap[on|off]  for that
UUID=67E3-17ED /mnt/67E3-17ED auto defaults,nofail 0 0
UUID=652F-FA93 /mnt/652F-FA93 auto defaults,nofail 0 0

**EDIT 2: lsblk --fs**

$ lsblk --fs
NAME FSTYPE FSVER LABEL UUID                                 FSAVAIL FSUSE% MOUNTPOINTS  
sda                                                                         
├─sda1       vfat   FAT32 EFI   67E3-17ED            196,9M     0% /mnt/67E3-17ED
└─sda2      exfat  1.0   8TB   652F-FA93              5,8T    20% /mnt/652F-FA93
mmcblk0              
├─mmcblk0p1  vfat   FAT32 bootfs D3E6-3F09                             436,8M    14% /boot/firmware
└─mmcblk0p2  ext4   1.0   rootfs cb6f0e18-5add-4177-ab98-e9f0235e06b3   42,7G    58% /

**EDIT 3: Changed fstab**

pi@raspberrypi:~ $ lsblk --fs 
NAME FSTYPE FSVER LABEL UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
sda                                                                         
|-sda1
|    vfat   FAT32 EFI   67E3-17ED                             196,9M     0% /mnt/67E3-17ED
`-sda2
     exfat  1.0   8TB   652F-FA93                               5,8T    20% /mnt/652F-FA93
mmcblk0
                                                                            
|-mmcblk0p1
|    vfat   FAT32 bootfs
|                       D3E6-3F09                             436,8M    14% /boot/firmware
`-mmcblk0p2
     ext4   1.0   rootfs
                        cb6f0e18-5add-4177-ab98-e9f0235e06b3   48,4G    54% /
pi@raspberrypi:~ $ ls -la /mnt
totalt 265
drwxr-xr-x  4 root root   4096 21 okt 16.28 .
drwxr-xr-x 18 root root   4096 10 okt 06.06 ..
drwxr-xr-x  4 root root 262144  7 nov 10.27 652F-FA93
drwxr-xr-x  2 root root    512  1 jan  1970 67E3-17ED

Thanks in advance for the help!