You can't use special characters such as ö ü etc, it must be exactly as in the >>>MRZ>>> field.
Be extremely careful as the OCR can misread and enter incorrect characters for the biodata page. Triple check and edit if necessary after uploading, then save.
Once you submit the application a QR code is generated, it's a little tricky to find in the portal, you download and print that QR code and take it to the Embassy the next morning 9:00 a.m. and pay, you will not get in without the QR code. Tomorrow is a Thai national holiday so likely it's closed.