Deployment fails: StaticAssetUploader

I've made a few attempts to deploy the Dev Portal but have been hitting an issue with the StaticAssetUploader Custom CFN resource. I've tried this using both SAR and manual deployments with SAM.

The Lambda function is hitting an Unhandled Promise Rejection with an AccessDenied error message. Relatively new to the project and am having some trouble spotting what's going wrong. Any ideas?

"reason": {
        "errorType": "AccessDenied",
        "errorMessage": "Access Denied",
        "code": "AccessDenied",
        "message": "Access Denied",
        "region": null,
        "time": "2023-02-07T17:57:51.280Z",
        "requestId": "***",
        "extendedRequestId": "***",
        "statusCode": 403,
        "retryable": false,
        "retryDelay": 31.37999690296416,
        "stack": [
            "AccessDenied: Access Denied",
            "    at Request.extractError (/var/runtime/node_modules/aws-sdk/lib/services/s3.js:710:35)",
            "    at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:106:20)",
            "    at Request.emit (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:78:10)",
            "    at Request.emit (/var/runtime/node_modules/aws-sdk/lib/request.js:686:14)",
            "    at Request.transition (/var/runtime/node_modules/aws-sdk/lib/request.js:22:10)",
            "    at AcceptorStateMachine.runTo (/var/runtime/node_modules/aws-sdk/lib/state_machine.js:14:12)",
            "    at /var/runtime/node_modules/aws-sdk/lib/state_machine.js:26:10",
            "    at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:38:9)",
            "    at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:688:12)",
            "    at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:116:18)"
        ]
    },

awslabs / aws-api-gateway-developer-portal

Deployment fails: StaticAssetUploader #611