Put a line of flux paste over pads and flat cable end.

Take the display module with face side down. Put the flat cable on cleaned pads on circuit board. Arrange the cable over pads to left free pad area a little less than 1mm from the left side (in second photo).

Set soldering iron temperature to 270C (520F). Tin the soldering iron and solder the cable to the board.

Be careful. During soldering keep the cable pins directly above related board pads. Try to avoid board overheat though very long heating.

Solder the first and last cable pin before soldering the rest, That will keep the cable in place during soldering the remaining pins.

Cable soldering is easier with thin oval T12-BC2 tip or other similar tip. Otherwise you will need to use a lot of flux paste to avoid solder clumping in large area with pad shorting in result due to thick tip that help solder spread where it is not desired.