You can download S3 Browser at https://s3browser.com
The account type you should choose is: S3 compatible Storage
Service Endpoint is: nl.dadup.eu
AccessKey & Secret key can be found in https://admin.tuxis.nl
After configuring the account you are automatically connected to your daDup storage.
From here you can create & delete buckets.
Once the bucket is created you can upload new files to your daDup storage.
But first: Create a daDup account
(if you don't have one).