I have been trying to design my own mod, and noticed I do not possess the male character assets in this folder.

C:\Program Files (x86)\Steam\SteamApps\common\Skyrim\Data\meshes\actors\character\character assets

I have tried doing a Validating file option on steam, but it always says there's 1 file it can't fix.

Is there a place I can download these assets ?

I think all vanilla stuff is located in their respective BSA files. I don't think there should be any meshes folder on a vanilla install.

That 1 file is likely nothing to worry about as it is a common issue with most people.