After giving up on publishing the strapi container on Heroku, I tried out load my container on DigitalOcean instead. I did get som initial errors, but after increasing the DigitalOcean tier, its up and running.
I wonder if this could the issue on Heroku too? As I am able to serve the website url, but not the admin page, giving the error of:
"Warning, an error occurred while requesting the api"
i will try change the Heroku tier from the free hobby dev server, and see if that solves the issue.