Error working with .FOR (fortran 77) code instead of f.90.

[sruthi162114001]

I am working on a project that requires running a source code written in FORTRAN 77. For this I tried running a Fortran sample model provided in the CisHackathon 2021 repository using yggdrasil by saving the model as a .FOR model instead of .f90 and it doesn't recognise the source file. Attaching a snapshot of the error. I would like to know if FORTRAN 77 codes can be run using yggdrasil or only fortran 90 codes are compatible. Any help would be appreciated.