Import a package without a .unitypackage file

Hello,

I've recently downloaded a complete pack of assets for a training tutorial, but there is no .unitypackage file inside of it, so when I copy all the files to my project folder all the connections are lost (materials don't have their texture assigned, prefabs with missing scrips etc). Is there any way to connect them automatically? because there are too many assets and is very tedious to do this manually.

Thanks.