Hi Mattia,
>I tried login to the cloud org with a local user and that works normally, but I see no vApps if I login with a LDAP users.
What are the users role? May be the local user use is Org admin and the LDAP users are just vApp users?
After you login as local user try sharing the vApp with an LDAP user then login as LDAP user and see if that vApp is available.
-KMK