On either Linux or Windows, you need admin/superuser rights for enrollment. It is due to the fact that armadito-agent retrieves your system UUID as an unique identifier. Indeed, it allows automatic association with inventory in GLPI.
Be sure that you got a valid enrollment key, or you won’t be able to enroll your agent.
To enroll/re-enroll an agent, just type the following with admin/superuser rights :
$ armadito-agent -t "Enrollment" -k "AAAAE-AAAAD-AAAAF-AAAAZ-AAAA5"