Neither of the CleverLoop camera models (indoor or outdoor) have batteries inside. You will need to use the plug-in power supply that comes with each camera.
The benefit of not using battery powered cameras is that you don't have to remember to change or charge batteries, so there is no need to worry about missing important video because your camera's battery has run flat.
Not being battery powered does mean you need to find a suitable location for CleverLoop cameras that is near a wall power socket (both indoor and outdoor cameras).
There are a few other options if you don't have an accessible power socket or are concerned that maybe your WiFi signal might not be the most stable where you want to place a camera. Here is a useful write up of what these options are, which has been written specifically for outdoor cameras as these are usually furthest from a power socket:
Finding a power source for indoor cameras is usually very easy. If in your case it's not, then the options for indoor cameras are very similar, but usually don't involve drilling holes! Here is a link on how to run power through an ethernet cable (known as Power over Ethernet or PoE) to indoor cameras: