Can I use only vms_identity without any multicharacter on qb-core?
No, this is not possible, because qb-core does not support the server of the possibility of not using multicharacters, you should choose the resource vms_multichars.
Can I use vms_identity with another multicharacter system?
Yes, you can use but you have to change this event esx_identity:showRegisterIdentity to this vms_identity:showRegisterIdentity in your multicharacter script.
