Marshmallow rom?

[hatv1]

Hello. I have a lg optimus f3 from sprint(LS720). My plan has been canceled for a while. I worked on downloading marshmallow ROM. I have everything set. I am using flashify and CWM and my device is rooted. I have found multiple sites that offer the download if I complete the survey. I used inspect element and skipped the survey. The sites had all said the downloads(there were 3 parts) was around 200 megabytes each, yet after using inspect, I downloaded it and it said it was only in the kilobytes (maybe 200-1000, I don't remember) and it was download has download safe, the site that gave me the site that wanted me to do a survey. Is this ROM legit or is it fake? And if it is, dies someone know where I can get the marshmallow ROM for my phone?