You can leave this blank.
As it says in the Mendix portal:
"If you are targetting Mendix 7.2 or 7.3, please specify the navigation profiles to use on phones and tablets. Make sure the profile identifier corresponds with the one defined in the modeler."
These profiles were only used in 7.2 & 7.3. We have since deprecated this feature.
The platform will now automatically detect the correct profile based on the device you are accessing from.