Typically, when you have files ending in .part01.rar , .part02.rar , etc., you need to keep in mind:

This specific version (v1.538.198.0) is an older build of the game from late 2022.

It looks like you've shared a filename for a specific (Part 8) of a Forza Horizon 5 game download.

Are you having these files, or were you looking for a newer update for the game?

You only need to right-click Part 01 and select "Extract Here" (using WinRAR or 7-Zip); it will automatically pull data from all the other parts to recreate the full file.