Reinstalling MacOS Sierra Problem (failing in the last 2 seconds)

Hi I’ve looked through forum and tried what I’ve found here. But still having issues.

my 2017 iMac 27” had HD (Mojave) erased but when I try to reinstall from the iMac the install comes up with one option which is macOS Sierra.

I try to install but it’s non stop error in last few seconds.

I have read that if I used APFS that Sierra won’t install. But I’ve no idea how to use the other suggestion I think it was called ‘extended journal’ as there’s no option showing at this stage?

Attempted several times this; to “start over using Option-Alt -R

Upgrade to the latest macos comparable”

but latest that shows is still sierra no other option.

I’ve no idea what I’m doing wrong. I’ve used ether wire to connect to internet and Often that hasn’t worked or just reverts to world with escalation mark and error code. My internet is working ok on my other computer.

I feel like I’m not making sense. I’m out of my mind trying to set this up. It was supposed to be simple delete HD and reinstall of macOS. Please can someone help? I’ve honestly run through everything I’ve found on here, I’m obviously doing something wrong as I have read it’s worked for others.

I also noticed even though erased in the disk utility is x base system is using 1.29 GB even though the HD was erased. Is that normal? Or relevant?

in the disk utility it states AppleAPFSMedia. Mac HD in disk utilities says 13.82 GB used out of 1TB

the first aid failed. Says first aid process failed.

On the utilities screen I’ve tried looking to download online. I’ve tried several times to reinstall but it only offers sierra.

I've tried to repair if there’s anything to repair. I just don’t know what to do.

Any help appreciated. Thank you