First, you need to have StarCraft II installed, or in the Linux case, the binaries must be downloaded. Map files are required as well.
Then a configuration file is required the proxy a bit, so create a file called sc2_proxy.toml with the following contents:
toml
[match_defaults.game]
map_name = "Automaton LE"
If you just want to test, use cargo run to launch. Then connect two bots to address 127.0.0.1:8642, both using only the join_game command. Setting env variable RUST_LOG to sc2_proxy=info would be smart as well, as otherwise even the game result is not logged.
For any real-world usage you most likely want to cargo build --release. and then use ./target/release/sc2-proxy (or target/release/sc2-proxy.exe on Windows). This is much faster, especially with settings that require doing lot's of packet inspection. It's also a static binary, so it can be easily deployed to matchmaking servers if you are running a bot ladder. See sc2_proxy.production.toml for example production config of a sc2 bot ladder.