That should be the first 054AP, which is being built in a dock shared with building 056As, the bow of one you can see in the picture.
The second 054AP should be built in the dock where the second 075 currently is. Either next to it, or in the same place where the second 075 is right now. Once the second 075 is launched, the modules for the 054AP should be craned and moved into the dock.
Both docks can hold another 054AP I can imagine in addition to the ones they are building now, so the third and fourth 054AP can be built in both docks respectively adjacent to the first two 054AP.
After that, HDZ should be working on Thailand's 071E, and hopefully, 054B or another 075 on the bigger dock. Probably building these ships adjacent to each other on these two docks.
They build the ships quick so they can free the dock. Plenty of space along the Huangpu River to fit the ships, although HDZ needs to clear all the remaining brand new 056As they are fitting right now.