For my 2018 model year MBP, all the "T3" screws referenced here and later in the guide were actually T4 for me.

Quote from paulius:

The annotation on the photo in Step 9 is inaccurate. The blue circle should be aqua/cyan coloured, while the two cyan/aqua coloured circles should be blue. No biggie, great disassembly otherwise.

I double checked it, it should be correct. There is only one medium screw and two small screws.