Tesouro Direto, bank-issued and private credit securities pay you in one of two ways: periodically, through coupons, or all at once at maturity. Either way, you don't need to do anything – the money arrives in your ARQ account automatically, already net of tax.
Periodic payments
Some securities pay interest periodically – monthly or semi-annually – instead of paying everything at maturity. These payments are called coupons.
When one of your securities pays a coupon, the amount goes straight to your ARQ account, already net of income tax when applicable. Your position in the security stays the same.
Payment at maturity
On the maturity date the security is redeemed automatically, with income tax on the earnings withheld at source when applicable. The net amount — your invested capital plus interest — is credited to your ARQ account.
The security then leaves your portfolio, and you'll find the payment in your transaction history.
Note that payouts are not reinvested automatically – the money stays available in your earnings account in reais for you to decide the next step.