Need help with Wifi extender configuration guide

I'm following this guide(CLI part) for the third time:

The second time I was able to connect my OpenWrt router (Tp-link TL-MR6400 v4) to my main router and download relayd. Then I had some problems and I restored the firmware to restart again.
Now, I followed all the steps the guide indicates, but I don't know if the router should automatically connects to the main router or if I have to type some other commands to achive this.

I have another question: when I try to turn on Wifi with "wifi up" or only "wifi" command, anything happens. The only way i found to turn it on is "ifconfig wlan0 up", and when I run it the wireless led starts alternate blinking and static light. Is this normal or is a problem?

I know that Luci should be better for a newbie like me, but for this versione of this model there isn't a stable version and when I installed Luci for the first time I didn't found which packages install to have what I needed.

I wish you could help me and sorry if I'm asking something too basic.
Thanks in advance