Cashapp's parent company, Square, led by Jack Dorsey, acquired Afterpay in 2021 in hopes of 'integrating cash app with afterpay.'
Afterpay customers manage their installment payments directly through the cash app, making it so much more convenient for the customers. Now, being under the same company, it is obvious that they will be accepting of one another.
This move was considered great for young shoppers on a budget and small vendors who can provide the option of 'buy now, pay later. In short, yes, afterpay does accept Cashapp.