As it turns out, the Apple Time Capsule only uses SMB protocol version 1 and NTLM for authentication. While this works with macOS without any changes, it often creates problem when trying to mount the the Time Capsule’s SMB share on a Linux system. With this parameters, mounting should work out of the box, given you have the cifs-utils (Debian/Ubuntu) installed:

sudo mount.cifs //10.0.0.1/Data /mnt/timecapsule/ -o password='yourpw',sec=ntlm,uid=<local user>,vers=1.0

If you have any problems or further insights, feel free to leave a comment.