These custom extensions are based on
You can build the binaries, if you have a local installation of JDK, with
$ ./mvnw clean package
If you don't have local JDK installation, but Docker is available, you can use the helper script
$ ./build-with-docker.sh
Both approaches will build the binary target/keycloak-extensions.jar.
Deploy the built JAR file into the $KEYCLOAK_HOME/providers folder of your Keycloak server (or copy it to your Docker image).
When running Keycloak in optimized mode, you'll have to run a build after deploying the JAR.
If you start Keycloak regularly, an implicit build will be performed.
See Keycloak Docs and Keycloak Guides for more info.