Redirect Error in Callback

[sam-c-freeman]

Hello! My co-engineer and I got this app working in this codebase but are getting this error when we moved the code to our actual app. Any thoughts? Can't find any good responses on the intuit developer portal. The issue did not occur when running this code base. We are trying to make the request from our server.

Access to XMLHttpRequest at 'https://appcenter.intuit.com/connect/oauth2?client_id=ABB8JQGKm8vuYkN4X5gDka2cyu7LRQ2tj8RwFVjlxSHB5I3vBm&redirect_uri=http%3A%2F%2Flocalhost%3A5000%2Fapi%2Fquickbooks%2Fcallback&response_type=code&state=829cL7W6-kx4uU1q4zjiD1cYsyQ6oneLGMSE&scope=com.intuit.quickbooks.accounting' (redirected from 'http://localhost:3000/api/quickbooks/connect_handler') from origin 'http://localhost:3000/' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is presen