Where does "MGE E47" white strip from Hard Drive attach?

Solution 1:

I found this video: How To Upgrade the Lenovo IdeaPad Gaming 3i With An SSD. The laptop name seems somewhat different but the hardware looks very similar (identical?).

Just watch the video, the relevant part starts at 1:08. In case the video becomes unavailable (and to make the answer standalone), I'm posting a picture and few remarks. This is how it should look like:

Note you need to (carefully) bend the ribbon cable twice, so it aligns with the socket. There's a movable flap you need to open to allow the cable to slide in with almost no force. If I interpret your photos right, your flap is black and already up (open). The cable should easily enter the socket with its blue side facing towards you. To secure the cable, flip the black flap towards (over) it. Gently try to pull the cable out. Properly secured ribbon cable cannot be easily pulled out of the socket.