Error when trying to obtain upload URL from huawei api connect

Question

I've successfully obtained the api key from huawei by creating a API client on the huawei connect portal (This was created by specying the name, N/A in project field and Assigned roles as administrator)

However when I try to call the API to obtain the upload URL so that I can upload my app to the store it returns with the following error : {"ret":{"code":205524993,"msg":"client token auth failed"}}

This is my powershell script I'm using to do this:

#obtaining API key

$tokenHeader = @{
    "Content-Type"="application/json"
}

# Token request payload
$tokenRequest = @{
    grant_type    = "client_credentials"
    client_id     = $ClientId 
    client_secret = $ClientKey 
} | ConvertTo-Json

# Get Access Token
write-host "retrieving access token"
$accessTokenResponse = Invoke-WebRequest -Uri $authUrl -Method POST -Headers $tokenHeader -Body $tokenRequest

#obtaining Upload url 

    $url = "https://connect-api.cloud.huawei.com/api/publish/v2/upload-url/appId=$appId&suffix=aab"
    $headers = @{
        "client_id" = "$clientId"
        "Content-Type" = "application/json"
        "Authorization" = "Bearer $accessTokenResponse.content"
    }
    
    $response = Invoke-RestMethod -Uri $uri -Method Get -Headers $headers