Multi-part archives work like a puzzle; you cannot extract the game if even one piece is missing.
Right-click on Forza.Horizon.5.part01.rar and select "Extract Here" or "Extract to Forza Horizon 5/" . Forza.Horizon.5.part07.rar
The software will automatically pull data from part07.rar and all other segments during the process. Multi-part archives work like a puzzle; you cannot
This means a part is missing from the folder. Ensure the sequence is complete (01, 02, 03...). Multi-part archives work like a puzzle