You must be an accredited investor to open a Willow 360 account. The most common ways to be considered an accredited investor are if you have an annual income for the past two years of $200K+ ($300K+ if joint) or if you have a net worth of $1M+.
There are other ways to be considered accredited; view this article for more.
At this time, Willow 360 is only available for individual/taxable accounts — not IRA or entity accounts.