Click on search and then select your fork of this repository.
Then Enable Automatic Deploys and then select the main branch (which is already done by default usually) and Click Deploy.
Once it has been deployed, go to Resources tab on heroku and enable worker (bash startbot.sh) dynos. (Do note that if you don't see any dynos in the Resources tab, then you must wait for about 5 minutes and then refresh your heroku page.)
You're now connected to lichess and awaiting challenges! Your bot is up and ready!