Try journalctl with the --no-pager flag, otherwise it will cut the and of the lines out from the output and we don’t see the exact error message.
Please, also show the output of the following commands
docker info
docker version
dpkg -l | grep docker
And the last question, where and how did you install Ubuntu 20.04? Is it ona local machine or in the cloud? Is it WSL on Windows or a physical Linux machine?
Also, please share a link to the guide you followed to install Docker.
And last:
Please, format your posts according to the following guide: How to format your forum posts
In short: please, use </> button to share codes, terminal outputs, error messages or anything that can contain special characters which would be interpreted by the MarkDown filter. Use the preview feature to make sure your text is formatted as you would expect it and check your post after you have sent it so you can still fix it.
Example code block:
```
echo "I am a code."
echo "An athletic one, and I wanna run."
```
This time I edited your question to add code blocks.