Thank you Garima - it worked. I find it a bit weird that it would be called "Create a vault" because it sounds like you are about to create a new vault, when actually you are just importing an existing one.
It must be very simple, but I can't see it... on my MacBook Pro I can use multiple vaults that are securely synced into my Google Drive. I want to do the same thing on my iPad, but I can only sync one vault.
How do I add the second one? Thank you!