Salesforce Community provides self registration feature so that external user could register for a login if required.
If you are interested to enable this option (From Setup, click Customize | Communities | All Communities, then click Manage next to the community name.), consider if your business requires the person account feature so that a self registered personnel will be tracked as a personal account in Salesforce.
If person account is not an option for you, you would need to consider implementing a dedicated account being used so that all self registered personnel will be treated as a contact under this specific account instead.
It is also recommended to ensure the profile that you are assigning to for self registered members have the appropriate permission set. Otherwise, the members may be able to view or edit data that you do not want them too.