I have never also used Coinbase multi sig vault, through search I found out that you need to actual have some extended private key and if you have that then you can follow this guide to restore it in electrum
https://bitcointalk.org/index.php?topic=2088713.msg20875786#msg20875786But if you don’t have them then read through this thread it might be similar to your problem
https://bitcointalk.org/index.php?topic=5381583.msg58999396#msg58999396I see on my coinbase account that I have around 800€ but no idea how can I put out to my bankaccount.
If you "see" your funds: are you talking about the wallet, or Coinbase the exchange? If it's Coinbase, you can sell your funds. If it's "the wallet", than I guess you have access already and can send your funds to an exchange to sell it.
Probably might be seeing the balance from an explorer by checking is address there, I doubt he has access already because he is asking of recovering the wallet