Cite the InsightFace library as the software reference and the ArcFace paper as the algorithmic reference. Do not cite a paper specifically named "w600k-r50" – that is just a model filename.
@articleinsightface, title=InsightFace: 2D and 3D Face Alignment Library, author=Guo, Jia and Deng, Jiankang, journal=arXiv preprint arXiv:2107.07461, year=2021 w600k-r50.onnx
The model name strongly suggests you are working with a face recognition model from the insightface library (specifically the Glint360K or WebFace600K trained ResNet50 model). Cite the InsightFace library as the software reference