no Let's Encrypt certificate

I don't get any Let's Encrypt certificate following your instructions.

The Setting:
- New set up Hetzner CX21 Cloud Server (Ubuntu 18.04, I tried Debian 10, too)

DNS-configuration |   |   |   |  
-- | -- | -- | -- | --
A |   |   |   |  
Type | Domain Name | Address | TTL |  
A | example.org | 'IPv4-Address' | 3599 |  
A | www.example.org | 'IPv4-Address' | 3599 |  
A | chat.example.org | 'IPv4-Address' | 3599 |  
A | cloud.example.org | 'IPv4-Address' | 3599 |  
A | video.example.org | 'IPv4-Address' | 3599 |  
  |   |   |   |  
AAAA |   |   |   |  
Type | Domain Name | Address | TTL |  
AAAA | example.org | 'IPv6-Address' | 3599 |  
AAAA | www.example.org | 'IPv6-Address' | 3599 |  
AAAA | chat.example.org | 'IPv6-Address' | 3599 |  
AAAA | cloud.example.org | 'IPv6-Address' | 3599 |  
AAAA | video.example.org | 'IPv6-Address' | 3599 |  
  |   |   |   |  
NS |   |   |   |  
Type | Domain Name | NS | TTL |  
NS | example.org | | 3599 |  
NS | example.org | | 3599 |  
  |   |   |   |  
CAA |   |   |   |  
Type | Domain Name | Value | TTL | Tag
CAA | example.org | letsencrypt.org | 3599 | issue
CAA | example.org | letsencrypt.org | 3599 | issuewild

Even after hours there is only the 'TRAEFIK DEFAULT CERT'...