Here you can find a list of issues that can arise during installation.
In RebornOS Welcome go to the advanced page and disable the internet check. In some cases it may be neccesary to select one of the alternative dns options. Afterwards restart the installer from RebornOS Welcome.
In RebornOS Welcome go to the advanced page and disable the checks manually, then restart the installer from RebornOS Welcome.
Unfortunately a number of issues may appear specific to one's hardware or environment. In these cases you will need to look up the error(s) in relation to your hardware. Since RebornOS is based on Arch Linux, Arch advice will be most relevant to you.