If a website offers "All Ullu Unrated Web Series in one 50GB Collection G folder," it is 100% a scam or malware trap. Legitimate streaming does not work via giant ZIP files.
If you are looking for specific series often featured in Ullu's top-tier collections, these are the most highly-rated by viewers: : Highly rated (8.3/10 on Collection G -- Ullu Unrated Web Series