GUR Rules Question | Golf Monthly

Ok, just been thinking about yesterdays captains day.. I was playing really well, but on the 17th there is a GUR. I hit my tee shot into said GUR, allowing me a free drop.

I took my drop from 2 club lengths (driver) from the edge of the GUR not gaining any advantage to the hole, infact leaving me needing to chip out onto the fairway leading onto me finishing with a 10... anyway back to my question.

On the edge of the GUR was a small arrow - I said to my playing partners is this correct, two club lengths no closer to the hole. they said yes thats fine, I carry on and take my drop.

On returning to the clubhouse, whilst having a beer I spoke to my mate and his dad and said about my 10 and that I hit GUR and took my drop from said location, to which he said, but there is a drop zone about 100 yards from the GUR, which I was not aware of (obviously what the arrow meant)

does this mean I made an illegal move by dropping two club lengths?