You could try using “Mask: Simple Shape” described in the following topic: Animating diagrams with "Mask: Simple Shape"
Basically you use the background of the post on one track and keyframe a mask to reveal the text on a second layer.
An alternative method would be adapting @jonray’s method for a handwriting effect (New tutorial on Youtube - handwritten or "write-on" text created with Shotcut and GIMP). You import a picture of the post and delete the text and use a gradient to fill the letters. You will have to fiddle around to make it work since the mask and your picture have to be aligned.