Newsletter form is erroring out

[Isaac-Tait]

I am using pliny with Behiiv in conjunction with the tailwind-nextjs-starter blog. When I test the newsletter signup I get an error message: Your e-mail address is invalid or you are already subscribed! The email address is valid and it is not already subscribed. When I check the devtools network tab I see a 401 error with a JSON Post request to the file newsletter.

I've set it up with Behiiv api keys in both production and dev environments. I'm sure I'm missing a step somewhere. Any pointers would be appreciated. Thanks.