I had problems like this too and through hours of trial and error, I got it working, Check out my bitcoin and bifrost settings found in repositories here
I can’t remember the exact problem, I think I remember I had my rpc urls wrong.
bitcoind refers to the bitcoin docker image and uses dockers networking.
But look at the docker-compose.yml files for a working example.
You can install everything I have to get bifrost working on testnet.