@girish Hi. I believe I am on: v6.3.5 (Ubuntu 20.04.2 LTS).
I actually got it working now using RSYNC instead of a Tarball.
However, using RSYNC takes a long time so my question now is why the Tarball method doesn't work - there may be no temp folder to keep the zipped file I suspect, or something like that.
My next question is what is the restore process - but I am not there yet.
Thanks.