Hi there, @DieterFleurackers, let’s jump right into this!
Just to clarify: have you tried downloading the entire external drive Backup, or just some folders from there?
If the entire content of the Backup was 1.5TB then it’d be better if you broke that into smaller batches, if you’re trying to download the content from our website.
Also, do you have our desktop app, installed on the new Mac?
Let me know more, and we’ll take it from there!