You can download it here: Akka gRPC Quickstart with Scala · Lightbend Tech Hub
The error is:
[error] (protocExecutable) lmcoursier.internal.shaded.coursier.error.FetchError$DownloadingArtifacts: Error fetching artifacts:
[error] https://repo1.maven.org/maven2/com/google/protobuf/protoc/3.15.6/protoc-3.15.6-osx-aarch_64.exe: not found: https://repo1.maven.org/maven2/com/google/protobuf/protoc/3.15.6/protoc-3.15.6-osx-aarch_64.exe
Can you update the protoc version?