try sudo chown -R user:usergroup /mount/path or sudo chmod -R -v 777 /mount/path
I had to do this after changing ntfs-3g to nfts3 to be able to write on the disk
I use my external drive as just download folder so if you have there more complex stuff not sure if that’s okay to do
My fstab has these arguments ntfs3 defaults,noatime,uid=user,gid=usergroup,nofail,iocharset=utf8 0 0 for the drive