You might not have one of the Smart WiFi LED bulbs.
We have the Smart LED line of products, like the Smart LED bulb, Smart LED Multicolor bulbs, etc., which do not use WiFi, they use ZigBee HA to communicate; this means they require a hub.
The Smart WiFi LED bulbs do use WiFi and thus can be setup without a hub.
Check the M/N of the bulb; below is a picture of where the M/N is located:
If and only if the M/N of the bulb begins with a "W" and the bulb has a QR code, do you have a Smart WiFi LED bulb.
If, generally speaking, the M/N of your bulbs starts with an "E" or a "Z" and the bulb has a QR code sticker on it, you have a Smart LED product which does require a hub in order to be used.
The Smart LED line of products cannot be setup without a hub. A hub would be required for use.
After pressing "Add Device" in the Sengled Home app, you have to choose which product you would like to add to your hub.
If you have one of the Smart LED line of bulbs, you would choose "Smart LED Lights (Need Hub)".