you are fine. pretty sure that “transfer cable” in the docs refers to things like this, also called “bridge cables”, for transferring files between two PCs. these are things with active electronics in the middle that typically implement a little network interface with two USB modems. you don’t want this for flashing TT firmware.
for TT-PC, you really do want a direct A-A cable with all the wires in it and nothing else. the TT has an OTG USB port just like an android phone does; it can act as a host or a device, and will go into device mode automatically on boot when it detects power coming in on the USB port. (so it won’t work without the power pin.)
it’s true and worth emphasizing, a direct A-A cable is not safe to connect two PCs. (i don’t exactly know why either host would draw power, but i guess the USB spec doesn’t prevent it, there’s no useful reason to do this, so why take chances.) so you will see people on the internet making scary pronouncements about how you should never use an A-A cable for anything and just throw it away if you see one. this doesn’t apply to the TT.
elsewhere on this forum, confused people have proposed using an A-A cable to connect the host port on a norns to a laptop, thinking they could somehow use the norns as a midi device this way. that would be unsafe and will not work, because the norns has normal USB host ports just like a laptop. again, this is unrelated to the TT and i’m only bringing it up here to avoid confusion.
