Yes, you can still apply for PTPTN loan even if you are a scholarship recipient.
This is because most scholarships are just partial scholarships. Therefore, you can then use the PTPTN loan to pay for the tuition fee balance and any surplus can then be used to cover your study and liviing expenses. The only rare exceptions, where PTPTN may not be eligible, are recipients of full scholarships, where the uni/college fees are already fully covered by the scholarship provider.