Companion status requires belief in the Prophet ﷺ at the time of meeting him. A subtler distinction applies to a Successor: meeting a Companion need not necessarily have occurred after the person had already embraced Islam; subsequent conversion may satisfy the religious qualification.
Case 1: Someone met a Companion while not yet Muslim, subsequently entered Islam, and fulfilled the other conditions. The person may belong to the Successor generation.
Case 2: Someone saw the Prophet ﷺ while not believing in him and accepted Islam only after his death. That earlier sighting does not itself establish Companion status.
Keeping the relevant person met and timing of faith distinct prevents the two generational definitions from being confused.