Trying to install Saleor app but getting the error "Registration failed: could not save the auth data."

Question

I have created a saleor app cloning the saleor-app-template

I have configured the manifest like this:

export default createManifestHandler({
  async manifestFactory(context) {
    const manifest: AppManifest = {
      name: packageJson.name,
      tokenTargetUrl: `${context.appBaseUrl}/api/register`,
      appUrl: context.appBaseUrl,
      permissions: ['MANAGE_USERS', 'MANAGE_ORDERS'],
      id: "saleor.app",
      version: packageJson.version,
      webhooks: [customerCreatedWebhook.getWebhookManifest(context.appBaseUrl)],
      extensions: [
        {
          label: 'Messages',
          mount: 'NAVIGATION_CUSTOMERS',
          target: 'APP_PAGE',
          permissions: ['MANAGE_USERS', 'MANAGE_ORDERS'],
          url: '/'
        }
      ],
    };

    return manifest;
  },
});

And I have created an async webhook

export const customerCreatedWebhook = new SaleorAsyncWebhook<any>({
    name: 'Customer created',
    webhookPath: 'api/webhooks/customerCreated',
    asyncEvent: 'CUSTOMER_CREATED',
    isActive: true,
    apl: saleorApp.apl,
    subscriptionQueryAst: customerCreatedSubscription,
    onError(error: WebhookError | Error) {
        console.error(error);
    },
    async formatErrorResponse(
        error: WebhookError | Error,
        req: NextApiRequest,
        res: NextApiResponse
    ) {
        return {
            code: 400,
            body: "My custom response",
        };
    },
});

const handler : NextWebhookApiHandler<any> = async (req, res, context) => {
    const { payload, authData } = context;
    const { saleorApiUrl, token, appId } = authData;
    console.log(payload.user?.email);
    console.debug(payload.user?.email);
    return res.status(200).end();
}

export default customerCreatedWebhook.createHandler(handler)

I'm running this app on localhost:3000 and I'm using ngrok for exposing this port and use the public URL on the saleor dashboard, besides that, my saleor dashboard is running on localhost:9000, The Saleor API and Database are running on docker, and I configured my APL with upstash APL configuration

I have these variables on the .env file for the app:

UPSTASH_URL=[url]
UPSTASH_TOKEN=[token]
APL=upstash

But then when I go to the saleor dashboard -> apps and try to install the external app, I get this error Registration failed: could not save the auth data.

I don't know what is missing or what I'm doing wrong

I also used the default APL configuration and the file .saleor-app-auth.json was created with these values

{"domain":"localhost:8000","token":"L8XSXDGjfOPJ5QyyUgpXWA05bvChpx","saleorApiUrl":"http://localhost:8000/graphql/","appId":"QXBwOjI1","jwks":"{\"keys\": [{\"kty\": \"RSA\", \"key_ops\": [\"verify\"], \"n\": \"xk51hxPXE4v7ERaBpoZBRU-NK_nKrK-lD-mOevJX_jigZyqGSRIGrald5K2f_YHMXVNzbuXHSO0JJWC-sjYuBCvmioKj5vr7cmTqUkLLIJl4pOXRGsGuj9YxTVeXnCBYKc2i60NAADlinN3oR1k1zhlne1cDuj6GBUxu31yCR88KLR1NIFreHLTzYjBp6IZSrGorS1_7OFT9QsKaroHWODCrV5PFAIosoaoTt16i677ZAylnQOJcfND-Vx5LH8qwavD8PIo3IzWZvOVQWRarDS4cLXbXPM4yNhDx1AFpm1UIyKP6ajIXp3v30SO3vzhtnU8earZMbOXSVOARtBwcTw\", \"e\": \"AQAB\", \"use\": \"sig\", \"kid\": \"1\"}]}"}

The app was installed correctly on the saleor dashboard, but then when I created a customer, the webhook throw SIGNATURE_VERIFICATION_FAILED signature verification failed