Mod archive is invalid or corrupted

After zipping the contents of 0.97 into Heroes 3 Complete (GOG version) I get the following error every time I try to download and install mods from the launcher:
Operation failed
Encountered errors:
wog: Mod archive is invalid or corrupted

Any easy fix or solution on my most likely noobish problem?

For anyone who may find this topic I’ll leave task to bug tracker:
bugs.vcmi.eu/view.php?id=2070

Can learn on own or not.