I estimate that you made around 36 ounces of dough, with a hydration of around 70%. That is a fairly wet dough, so it is not surprising that you found the dough to be wet and had to add more flour. Kneading a dough batch of over two pounds is not an easy task, and even more so if the flour is a high-gluten flour (I note that you didn't indicate what flour you actually used). Under the circumstances, it is quite easy to end up with a lumpy dough. I believe the problem is more one of not properly and completely hydrating the flour. One way to improve the situation (i.e., improve the hydration of the flour) is to sift the flour and gradually add it to the water while you are mixing it it into the water. The ADY has to be hydrated in warm water (around 105 degrees F) for about ten minutes, but the salt and sugar can be added to the water and dissolved into it. The rehydrated ADY can be added to the water mixture so long as the flour is promptly added to the water mixture. If you let the dough rest for a few minutes here and there during the kneading process, that will also improve the hydration of the flour, and especially so if you are using high gluten flour. As for the oil, I normally add that last, even when hand kneading, although it is also quite common to add it to the water mixture.
I would not attempt using the windowpane test at the end of your hand kneading. That is more appropriate to bread dough than pizza dough. With proper fermentation, the dough will in due time (after a reasonable period of fermentation) pass the windowpane test, even though it might not when first made. With pizza dough, you want it to be slightly underkneaded (yet smooth).