I would ask if its an IRA or a taxable account. If its an IRA, here is information I found from searching. You should not need to create an account with Stifel.
https://investor.vanguard.com/inherit/ira"Steps you'll take to inherit an IRA
Here's a general, step-by-step process that shows how inheriting an IRA will work. Find out what you’ll need before you get started.
Let us know about the person who passed away: The first step will be letting us know. That way, we're able to update our records and take some precautions on our end (for example, freezing the account to protect it from unauthorized activity).
Tell us about yourself: We'll ask you for some basic information, like your email address, Social Security number, date of birth, and a few other details.
Begin the transfer process: Different options for inheriting are available, depending on who you are. So we'll start by asking if you’re the spouse or non-spouse."
Inheriting an IRA as a non-spouse
Your only option is to transfer the IRA into an Inherited IRA in your name. Then you'll begin taking withdrawals according to a timeline set by the IRS. See the IRS withdrawal rules for Inherited IRAs."