I managed to reach the point “Starting ghost”:

 Downloading and installing Ghost v3.40.2
✔ Finishing install process
? Enter your blog URL: https://congral.tech
✔ Configuring Ghost
✔ Setting up instance
+ sudo useradd --system --user-group ghost
+ sudo chown -R ghost:ghost /var/www/ghost/content
✔ Setting up "ghost" system user
ℹ Setting up "ghost" mysql user [skipped]
+ sudo mv /tmp/congral-tech/congral.tech.conf /etc/nginx/sites-available/congral.tech.conf
+ sudo ln -sf /etc/nginx/sites-available/congral.tech.conf /etc/nginx/sites-enabled/congral.tech.conf
+ sudo nginx -s reload
✔ Setting up Nginx
? Enter your email (For SSL Certificate) nikolaj.ivancic@congral.com
+ sudo mkdir -p /etc/letsencrypt
+ sudo ./acme.sh --install --home /etc/letsencrypt
+ sudo /etc/letsencrypt/acme.sh --issue --home /etc/letsencrypt --domain congral.tech --webroot /var/www/ghost/system/nginx-root --reloadcmd "nginx -s reload" --accountemail nikolaj.ivancic@congral.com
✖ Setting up SSL
+ sudo mv /tmp/congral-tech/ghost_congral-tech.service /lib/systemd/system/ghost_congral-tech.service
+ sudo systemctl daemon-reload
✔ Setting up Systemd
+ sudo systemctl is-active ghost_congral-tech
+ sudo systemctl start ghost_congral-tech
+ sudo systemctl is-enabled ghost_congral-tech
+ sudo systemctl enable ghost_congral-tech --quiet
✔ Starting Ghost
One or more errors occurred.

1) SystemError

Message: Your domain name is not pointing to the correct IP address of your server, check your DNS has propagated and run `ghost setup ssl` again

Debug Information:
    OS: Ubuntu, v18.04.4 LTS
    Node Version: v12.18.0
    Ghost Version: 3.40.2
    Ghost-CLI Version: 1.15.3
    Environment: production
    Command: 'ghost install --auto --db=mysql --dbhost=localhost --dbname=ghost_production --dbuser=ghost --dbpass=84bc933f1f8518e08f86d4ea37f39abfa8c2e19bbc0c8b5e --dir=/var/www/ghost --start'

I do believe that DNS stuff is set correctly:

λ ping congral.tech

Pinging congral.tech [104.236.19.5] with 32 bytes of data:
Reply from 104.236.19.5: bytes=32 time=32ms TTL=54
Reply from 104.236.19.5: bytes=32 time=33ms TTL=54
Reply from 104.236.19.5: bytes=32 time=43ms TTL=54
Reply from 104.236.19.5: bytes=32 time=32ms TTL=54

Ping statistics for 104.236.19.5:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 32ms, Maximum = 43ms, Average = 35ms

c:\work
λ ping blog.congral.tech

Pinging blog.congral.tech [104.236.19.5] with 32 bytes of data:
Reply from 104.236.19.5: bytes=32 time=34ms TTL=54
Reply from 104.236.19.5: bytes=32 time=31ms TTL=54
Reply from 104.236.19.5: bytes=32 time=31ms TTL=54
Reply from 104.236.19.5: bytes=32 time=31ms TTL=54

Ping statistics for 104.236.19.5:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 31ms, Maximum = 34ms, Average = 31ms

Nevertheless, “both https://congral.tech/ghost” and “https://blog.congral.tech/ghost” fail to render the ghost page

What am I missing???