First of all, if all the normal zombies go back to their refugee models, it's because you have either...

1. Conflicting Workshop Addons - To solve, look through all your other addons' contents via Gmod's ingame prop browser. If any contain the HL2 zombie models, disable them and restart. If you want to quickly check if it is an addon before starting this, simply disable all other addons and test.

2. Zombie models in the main garrysmod directory - Go to your "C:\Program Files (x86)\Steam\SteamApps\common\GarrysMod\garrysmod" folder. If there is a "models" folder, open it. If there is then a "zombie" folder inside, delete it. If there is no zombie folder then this was not the cause.

3. Content Packs - This should be obvious, pirated content packs for HL2 games will contain all a game's content, including the HL2 zombie models, and so will cause a model conflict. So if you have ever had any of these, delete them. Pirating's bad, mkay?

Now, about the zombine skins

Do you know how to read descriptions? you NEED Half Life 2: Episode 1 downloaded and mounted on Gmod so the zombines can appear