So, these are Tuya (Smart Home) devices with an Amazon psudo-branding. Initial connection is via Bluetooth, and you shouldn't normally need to turn off the 5GHz radio. I've set these very devices up though I don't have any here, and they are usually incredibly straightforward.
Are you using the Tuya, Smart Home, or another app? From memory, the Tuya app itself is usually at least a point version ahead of the others!