Zbt wg827 (mt7621)

Hello friends! Need help!
Well I just ordered ZBT WG827 from AliExpress and the seller promise me to install OpenWrt 22.03 but he don't do it and install firmware "LEDE Reboot SNAPSHOT 17.01 21.1110_173058"
Well maybe anyone could advice me how to install Openwrt 22.03.03 on this device?
How I can install firmware if the model is not on the device list OpenWrt ?
Maybe someone already done it?
Please give me any advice for understand this situation.

You can't, or at least shouldn't.

Ask for a refund.

I don't have this device but with the devices i have I can tell you that the WIFI speed with the old lede 17.01 is much better than with the OpenWrt recent versions