The OM-1 is a very new camera model.
Support will be added the next time the RAW library is updated. Right now I see no non-beta update, fotoARRAY is using 0.20.2 already which is from 10/2020. The EXIF information is loaded from the RAW files already.
However you will see the thumbnails when you store RAW+JPEG since the preview can be loaded from the sidecar JPG file. If you can extract the previews to a subfolder called _preview, i.e. with EXIFTOOL, fotoARRAY can also find them there.
Please also note when you have developed versions of the RAW in a subfolder with he name _final it will be loaded as second thumbnail. Such a version is meant to visualize the edited version of an image. By clicking on the "eye" button in the lower left corner of main screen you can switch between the initial and edited version. If the developed version was loaded from directory _final you will see a lock icon. This means any rotation command will be ignored for this preview since the edited version should have any necessary rotation applied to.