Trouble installing Ubuntu Server 20.04 and 18.04

Recently I’ve tried to install in an old machine (not that old) Ubuntu Server, starting with the 18.04 LTS, and after that failed, trying 20.04 LTS.
In both, the installation would run smoothly until it will prompt out and error and restart the installation process.

Even after this error, if I shut down the machine and restart the server appears to have been installed. But when I open and try to login with the user and password provided always says that is an incorrect login (even with the easier passwords that I could think of).

Does anyone know why these errors appear and why the login information is not correct? I already made sure that the layout of the keyboard was correct in every step.