Tribal affiliation of Ger and Arab Rav

Shalom Rabbi, regarding conversion during the period of the tribes, the story of Ruth the Moabite who converted and married Boaz from the tribe of Judah is well known, and therefore joined the tribe of Judah. ​​The question is, what will happen to a man who converts, how does he join any tribe? If at all. The same applies to a couple who converts. Likewise, when the Israelites left Egypt, the Torah states that they left 600,000 foot soldiers and in addition, the Arv Rav also left with them, but for some reason in the censuses of the population, the Arv Rav is not visible in the census. Was he assimilated into the tribes? And if so, how?