If you use the site in German replace "balance" with "Guthaben", "my Bitcoin.de" with "mein Bitcoin.de" and "Overview" with "Übersicht"
From there you should be able to withdraw your coins to the wallet of your choice. Here's an overview of Bitcoin wallets:
https://bitcointalksearch.org/topic/general-bitcoin-wallets-which-what-why-1631151
For desktop I'd personally recommend Electrum. If you want to store larger amounts I'd recommend getting a hardware wallet such as the Trezor (available on trezor.io) and Ledger (available on ledger.com), bought directly from the respective manufacturer.
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In addition to being more secure using Google Authenticator also rids you of the waiting time for the confirmation Email. Just make sure to make a paper backup of the displayed 2FA key as well, in case you lose your phone.