Microsoft have issued an update to help fix the problem installing build 18362 on Windows Insider machines on the slow ring. There was an error causing build 18362 to fail during the upgrade process from 18356, which meant Windows Insiders on the slow ring where stuck on an old build. Microsoft have now fixed the problem via a cumulative update 18356.21 (KB4496796). After installing the update you will be able to install 18362 once Microsoft re-release the build in a couple of days.
It looks very much like 18362 will be the build that rolls out to Windows users later this month.
We have released Build 18356.21 (KB4496796) to Windows Insiders in the Slow ring who are currently on Build 18356.16. This update will get Insiders who are on Build 18356.16 back into a good state so they can update to Build 18362. We are allowing a few days for this update to roll out before offering Build 18362 – so that means Insiders will still not see Build 18362 offered after updating to Build 18356.21. But stay tuned!