Using a TP-Link Travel router to set up static IP's?

I'm trying to configure a TP-Link Travel Router so I can create a separate network from public wifi. I'm using "Hotspot Router mode" explained on page 10 of this manual.

So far it works. I'm able to enter the SSID/Password of the public WiFi and then broadcast a new network. Devices can connect to this new network using a separate SSID/Password.

However, I want to make a network where the local IP's of devices that connect always remain the same. In other words, when I connect to a new public wifi, I want all of my devices to remain mapped to the same IP. Does that make sense? I'm not sure if this is the default behavior of the router as I've only been experimenting on one network. But I can foresee this possibly being a problem when I connect to a new network.

I basically have a situation where I need the IP of device A and B to always be 10.0.0.2 and 10.0.0.3 for example. I don't want to have it always randomly assign.

Any insight?

Thanks!