@Javier Morales Escudero if you are successfully connected to the SoftAP you can also open the Out-of-the-Box Experience (OOBE) by typing 10.1.1.1 as your browser URL. 10.1.1.1 is the IP address of the SoftAP. If you connect through ethernet and know the device's IP, typing that to the browser as well.
Ssh to the device is blocked by default and you'll need to generate the ssh user as a part of OOBE.
However, as you mentioned a new browser tab should open automatically after successful connection to SoftAP. I have noticed that sometimes browser's settings may block it. I unfortunately don't have good information/documentation in terms of what settings to check.