Hello,
thank you for your answer, i will write you at the mail adress if needed 
Well, in Dolibarr, users are the users that can log in; members are just a database of people (Dolibarr is a CRM).
The main idea is that users from Dolibarr are users from LDAP/Cloudron (and this part works well, the script works great to copy users from LDAP to Dolibarr); but members are created in Dolibarr, then used to give access to other applications (and for that, i use a Keycloak managed by Cloudron).
As Dolibarr allows to copy members from Dolibarr to LDAP (with the integated module, cf. first picture), i thought i can copy member in a LDAP OU (for example, ou=members), then use Keycloak to use them. But if the Cloudron LDAP is read-only, nope.
Maybe it's possible to install a LDAP app (and not use the Cloudron ?), but i don't think there's an app in the store...