Hi Fabrizio,
If I understand correctly, you're concerned if the account used in the F5 Management Pack discovery wizard needs to be an Active Directory account. No, not at all. It could be just a local device account (used for basic authentication). But it needs to have an admin role on the F5 device. On the other hand, you could use the Active Directory integrated authentication mapping through the 'Remote Directory Tree' configuration (on the F5 device): Users :: Authentication :: User Directory :: Remote Active Directory :: Remote Directory Tree, where you would enter the AD organizational group (OU) which contains the user accounts for accessing the F5 device. You can have this OU / user group have admin rights on your F5 device.
Julian