Hi,
i highly reccomend to read some documentation :D
if your frontend is just static html and does not need to be pre-processed or something, you don't need the build step - so the errors regarding hugo are not relevant (btw: hugo is an awesome tool to create static sites - https://gohugo.io/)
all other configs are described in the s3 plugin docs http://plugins.drone.io/drone-plugins/drone-s3/
if you just want to push all files in your repository, you can just write source : **/*
Eventually I hope to support pluggable remotes using Go plugins [1]. This would allow the community to expand the functionality of Drone without having to introduce new modules to Drone core. This is something I would explore further once Go 1.11 is release, since it includes some fixes that will be required.