What version is your ArchiCAD and what version is the DWG file you received?
Maybe the AC version is older and the DWG file is newer?
If that is not the problem what is the exact error message you get when trying to open the DWG?
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AMD Ryzen 1700X CPU, 48 GB RAM, Nvidia GTX 1060 6GB, 500 GB NVMe SSD
2x28" (2560x1440), WIN10 PRO ENG, AC20-AC26
Loving Archicad since 1995