I erased Macintosh HD in disk utility, now I can't reinstall macOS Big Sur

So I wanted to reset my 2019 Macbook Pro, so I used CMD + R and went to disk utility and erased Macintosh HD... I then went to reinstall MacOS Big Sur and I got about halfway through the reinstallation but then it stopped and went to a prohibitory symbol with a black background and just states to go to Apple Support.

What have I done wrong, how do I fix this and get my Mac to reset properly?

Please any advice?

If the recovery mode on your Mac won't let you install macOS, then the next trick is "Internet Recovery Mode". See this web page for a description of how to use it to reinstall your Mac's OS: https://www.macworld.co.uk/how-to/recovery-mode-internet-3636668/#internet%20recovery

The important thing to note here though, is that you need to be connected to the Internet in order to use it (the clue is in the name) and that a large download is involved, so it will take some time to start the recovery mode. I think it's about 12GB or so.