"If you do lose your job, a UBI probably won’t give you enough to pay your existing bills, or even just keep you fed, clothed and housed."

I think it'd do just that by definition, and if you want to maintain a higher standard of living without a job, savings, investment, insurance are all options to consider.

On the note of cost:

"It works out to a maximum of $4,452 per person per year, or $371 per month."

This seems to be an accounting issue. With a universal scheme, everyone pays in and everyone gets something out of it. So it's not strange to account for the payout as a negative tax burden, as is is done here: https://works.bepress.com/widerquist/75/

Shifting focus to net transfer, which makes financing it on a decently livable level a lot more sensible. Negative Income Tax models do this explicitly, if you want to guarantee an income that way and use that term.