I also have the same error.
I'm installing the "ONLYOFFICE_DocumentServer_Win-install.v3.0.exe" on Windows 10 and it goes pretty well until the IIS configuration step.
It says "There was an error during the IIS configuration process" and then rollbacks all installation processes.
Is there any way to install IIS Web Site manually and skip that step? Because after the rollback process, there is still a web site added on the IIS with an error icon named "ONLYOFFICE DocumentServer". And in the next try of installation, it asks me if I want to skip the IIS configuration process. So if I somehow make the IIS configuration manually, I think everything will be fine.