@AvidLearner 

You can indeed setup VLANs on the switch, but it will be tough to get this trunked to the WAN connection in a non omada router.   You could (and people have) used non omada hardware to setup VLANs and DHCP scopes etc, but in honesty dmac above is correct. 

If you just want one VLAN (default) and a couple SSIDs you are likely fine, other vlans, DHCP pools etc get the router

For the small extra outlay that it costs to add an ER605, just do it.. otherwise you will wish you had hours later when ripping your hair out!   :)