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#msg20875786

But 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#msg58999396