Dear Cui,
Please check that the path and name of the OLAF file in your AeroDyn input file.
The file “IEA-15-240-RWT_OLAF.dat” is available on Github. (IEA-15-240-RWT/OpenFAST/IEA-15-240-RWT-OLAF at master · IEAWindTask37/IEA-15-240-RWT · GitHub)
Best regards,
Yao.Tian