Why does port 5432 error appear when installing postgresl?

Question

PostgreSQL

Good afternoon.
I installed Ubuntu 20 on the virtual machine. And I immediately started installing postgres via apt-get install.
At the end of the installation, the following message appears

What is this and how to deal with it?
Google gave options that you need to specify a specific version of postgres, but this did not help.

Answer 1

Why do you think that this is a mistake and that this should be dealt with somehow?