Do I really get to correct Steve Jones?  Nah, I must be wrong.... SQL Server 2017 doesnt strictly require WSFC for AlwaysOn AGs.  For example, on Linux there is no WSFC but AGs work fine using the "EXTERNAL" option in the wizard.  I must confess that I've not set it up without a cluster, but I bet it would work.  This guy is doing it:  http://sqlha.com/2017/02/22/alwayson-availability-groups-no-underlying-cluster-sql-server-v-next/  here is another approach:  http://www.sqlmastersconsulting.com.au/SQL-Server-Blog/sql-server-2017-read-scale-out-availability-group

MS documentation:  https://docs.microsoft.com/en-us/sql/database-engine/availability-groups/windows/read-scale-availability-groups

In any event, I dont think you are getting automatic failover without the cluster though.