A redownload fixed it.

Size was almost identical but not quite. It is still very strange that all four files were of the same product which had the problem. All files from the other products I downloaded in the same purchase did not have this problem.

The filesizes you mentioned are not accurate enough:
For SAV_LucientHair_1 the failing zip was 45.195.153 bytes, the correct one as 45.198.073 bytes. Windows reports for both of them 43.1MB.

Must have been a server hickup (assuming you use multiple servers)