Terraform retrieving existing GCP secret as Data - google-cloud-platform

Question

Trying to implement a Data Module for referencing a 'Robot Account' for Terraform.
I get the folowing errors:
Error: Reference to undeclared resource
on main.tf line 7, in provider "google":
7: credentials = data.google_secret_manager_secret_version.secret
A data resource "google_secret_manager_secret_version" "secret" has not been
declared in the root module.
Error: Reference to undeclared input variable
on datamodule\KeydataModule.tf line 3, in data "google_secret_manager_secret_version" "secret":
3: secret = "${var.Terra_Auth}"
An input variable with the name "Terra_Auth" has not been declared. This
variable can be declared with a variable "Terra_Auth" {} block.
With the following main.tf:
module "KeydataModule" {
source = "./datamodule"
}
provider "google" {
credentials = data.google_secret_manager_secret_version.secret
project = "KubeProject"
region = "us-central1"
zone = "us-central1-c"
}
resource "google_compute_instance" "vm_instance" {
name = "terraform-instance"
machine_type = "f1-micro"
boot_disk {
initialize_params {
image = "ubuntu-cloud/ubuntu-1804-lts"
}
}
network_interface {
# A default network is created for all GCP projects
network = google_compute_network.vpc_network.self_link
access_config {
}
}
}
resource "google_compute_network" "vpc_network" {
name = "terraform-network"
auto_create_subnetworks = "true"
}
The keydataModule.tf:
data "google_secret_manager_secret_version" "secret" {
provider = google-beta
secret = "${var.Terra_Auth}"
}
The following variables.tf for creating the 'Terra Auth' variable:
variable "Terra_Auth" {
type = string
description = "Access Key for Terraform Service Account"
}
And finally a terraform.tfvars file, which in this case houses the secret name within my GCP account:
Terra_Auth = "Terraform_GCP_Account_Secret"