Canon EOS R5C Manual page 572

4.
Select [Add a device to connect to].
5.
Press < >.
6.
Pair the devices.
When the [Pairing] screen appears, press and hold the <W> and <T>
buttons on the BR-E1 simultaneously for at least 3 sec.
After a message confirms that the camera is paired with the BR-E1,
press < >.
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