docker-compose volumes

It seems you are using an absolute path located inside C:\Users dir, that didn't work for me too, if you are using Docker-Toolbox see below. Forwarding the ./ relative path in volumes section will automatically get resolved by docker-compose to the directory containing docker-compose.yml file (for example, if your project is in %UserProfile%/my-project then ./:/var/www/html gets /c/Users/my-name/my-project:/var/www/html).