This plugin helps you out if you need to have the ability to select one or more user roles. Roles can be chosen with a select element (single or multiple choice), checkboxes or radio buttons. Roles can be returned as a role name or a role object.
You also have the option of specifying allowed roles. This lets you control the roles users are allowed to select.
This ACF field type is compatible with both ACF 4 and ACF 5.