I have a simple Unifi setup. One USG (router/gateway), Switch, Access Point, Cloud Key (camera recorder).
Instead of buying another Unifi Access Point I was thinking of just using an existing Archer C7.
I would have it wired. How should I configure it?... Just give it the same SSID/Password?
I have an IoT VLAN, will it be possible to use it with the Archer C7?
For an investment of $0, an Archer C7, v2 or later, is a great AP.
Multiple SSIDs can be configured per radio. The SSIDs can be bridged to specific VLANs within the unit. The VLANs can be isolated with firewall rules in the Archer C7. The VLANs can be managed by the switch and "trunked" together as tagged over the Ethernet. Within the limits of reasonable sanity, several SSIDs and VLANs can easily be accommodated.
Specific config details would need to know a little more about how and what you want to connect up.