This is kind of goofy with how Ubiquiti doesn’t do well at supporting SNMP.  For one thing, they don’t support it through the controller, only directly to each AP.  But, you have to enable it at the controller to have it flip the switch on the APs so they’ll respond.  They really want you to use the API, which is great if you’re a programmer.  I am not.  I’m a router jockey, so I like SNMP.  Anyway, after finding and downloading the MIBs I had a look through them and sorted out a couple of OIDs I was interested in.  Specifically, client count per radio and Eth0 bits in and bits out.  Here’s what I loaded into Telegraf.  You need a separate inputs section for each AP you want to monitor.  Nope, not really an “Enterprise” approach.

[[inputs.snmp]]
agents = [ “192.168.x.x:161” ]  ## The IP of a single AP.
timeout = “5s”
retries = 3
version = 1
community = “RO_Community”
max_repetitions = 10
name = “UnifiWiFiOffice”
[[inputs.snmp.field]]
name = “Bits.Out”
oid = “1.3.6.1.4.1.41112.1.6.2.1.1.12.0”
[[inputs.snmp.field]]
name = “Bits.In”
oid = “1.3.6.1.4.1.41112.1.6.2.1.1.6.0”
[[inputs.snmp.field]]
name = “2.4.Clients”
oid = “1.3.6.1.4.1.41112.1.6.1.2.1.8.0”
[[inputs.snmp.field]]
name = “5.0.Clients”
oid = “1.3.6.1.4.1.41112.1.6.1.2.1.8.3”