If there are Fusion Brain devices connected to the PC, the Configurator will show them in the popup. To select one of them left click the instance ID you want. For instance the only instance ID connected here is "4&28731668&0&2". Please note that your number will not be the same as this. It is a unique random number that is generated on the system level. It will have the same form with the numbers and ampersands in the same positions more than likely, but that ends the similarities between this example and what you will experience.
If you have multiple Fusion Brains on the same computer, there will be multiple ID's shown. To determine which is which, click the identification icon (bottom left) and it will flash the LEDs of the selelcted Brain. If you connect or disconnect a Fusion Brain while this screen is open, you can rescan the computer and update the list by clicking the refresh icon (2nd from the left on the bottom).
After you select your ID, click the checkmark icon to accept it. If you do not want to accept the ID, click the x icon to cancel.