Image Rendering Cant Send Url To slack

I cant see rendered images on slack alerts.

Configuration:

unified_alerting: true
[unified_alerting.screenshots]
capture = true
max_concurrent_screenshots = 5
[external_image_storage.local]

Using a custom domain name. Enabled google oauth2. Slack cant see images on itself becuase cant login grafan from slack

Dashboard UID and panel id is included to alerts.

Installed plugin with CLI like explained here:

Plugin can render images. Checked from logs:

logger=rendering renderer=plugin time level=debug msg=“Calling renderer plugin” req=“url:"http://localhost:3000/d-solo/somerandomkey/metric_name?orgId=1&panelId=44&render=1\” width:1000 height:500 deviceScaleFactor:1 filePath:"/var/lib/grafana/png/somerandomkey.png" renderKey:"somerandom key" domain:"localhost" timeout:10 authToken:"-""

I can see rendered image on the server.

I can see image with https://domain_name/d-solo/somerandomkey/metric_name?orgId=1&panelId=44&render=1

With custom message template or without is not differ the case.

My question:
1-) At least i want to see the image url from slack. But cant see. Why?
2-) Is there anything wrong in my configuration?

It can send images via email btw