There are 6 pins on the relay. I’m gonna try what you’ve suggested.
Maybe there was a problem with the FTDI. I was using that to power the ESP. So I’m going to use my breadcrumb power supply 3.3V and 5V.
I’ll post a new message after trying that (tonight).
Thank you very much again. It works! I mean, now the relay can click thanks to the ESP.
However, there is something I have to fix, after 2 minutes, the ESP is not anymore accessible. I restart the ESP and all fine but only for several seconds/ few minutes... I'm using a USB charger, maybe it's not suitable to power an ESP and a relay. It happened while the relay was on. I should try if the problem occurs when the relay is off. I will write my result here, it could be useful for other beginners.
Thanks again Aledrus!