- Well maybe he actually tested it but i doubt that.
Second: the instructions on that page are totally wrong. There is no TWRP build for billie.
Third and most important: dont trust that website (getdroidtips) ! I often see articles for many custom ROM flashing instructions etc on that site, they are mostly just copied from some XDA post or copypasta from another device.
The author has ~5000 posts with 20 per day and misinformation on the first look - i call BS.
EDIT: also please don't post stuff like this in ROMs & development. it belongs to Q&A
EDIT2: i sent them an email hoping they'll take it down or at least correct the information