A payday is a type of unsecured loan, but it is usually repaid on the borrower's next payday, quite than in installments over a period of time.
When the time of paying the has reached, the lender will debit your account.
In brief, no: The lender doesn't report your funds to the credit bureaus, so paying the loan does not construct credit score.
The lender for PayPal Enterprise is WebBank, Member FDIC. No.