Framework Laptop Community

Hi, I was thinking of getting a Framework 13 and putting Linux on it.

So I was looking at the Ubuntu installation instructions and it says a "Storage Expansion Card" is required to install. I click "view" to see what that is, and the item page says it's a 250GB Type. The URL provided goes to a dead link, but I think that means a "250GB (2nd Gen) Storage Expansion Card" for $45 on the configuration page. I've installed Ubuntu before, but I just used a plain USB stick, and the instructions aren't clear on whether that's enough or whether I need to use their specific drive for some reason.

So my question is: when I'm configuring a Framework 13, do I need to add a 250GB expansion card, or can I just use a USB stick that I already have (to install Ubuntu)? Thanks.