Invalid customer transaction identifier.APPLY : ORA-01403: no data foundORA-01403: no data found in Package AR_RECEIPT_API_PUB Procedure Apply

One of the possible reason is Invoice already paid.

You can validate with below query. 

select * from ra_customer_trx_all where trx_number = '1'

note customer_trx_id from the above query.

select * from ar_receivable_applications_all

where applied_customer_trx_id = <pass customer trx id>

note cash_receipt_id from above query 

select * from ar_cash_receipts_all

where cash_receipt_id = <pass cash receipt id>