I come with the solution!
There are a few important notes the tutorial left out.
To succesfully create the mod pack you must:
1. Make sure all your folders and files are in the correct directories.(Mods in mods folder, coremods in coremods folder, etc.)
2. when you compress the mod pack DO NOT compress the folder your files are in. Instead select all files and right click to compress.(I would put in a screen recording but i don't know how to.)
3. Also when you are compressing the jar mod files (Forge) select all files and compress.