Sign in with an account that has role = admin (stored on the server your API uses).
Two different URLs — this is normal
https://adminapp.winkmeet.comhttps://app.winkmeet.com
The API is not on port 3000. Port 3000 is only ADMIN_PORT where this small Express app serves pages.
After you submit, this admin server calls {Backend API}/api/admin/auth/login — check your admin_panel/.env.
Want https://… here instead of localhost? Deploy this admin_panel service (Railway etc.) — your API URL in env stays wherever the API is hosted.