Do you have the schematic or other information regarding the ebay board?
I don't but it there is a lot of information on the LT3042 datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/3042fb.pdfI think the board is pretty close to the schematic on the datasheet first page.
I just blundered around unsoldering resistors (and accidentally unsoldering and resoldering a capacitor!) until the output was determined by the external resistor I had soldered. The board is clearly labelled underneath as shown in the attached photo. I think it was R6 I had to unsolder. You can also follow the traces from the chip if your eyesight is up to it (mine is getting a little dodgy now-a-days!)
You also need to connect the enable to positive VIN (check on the datasheet).
It would be neater to just connect enable to VIN on the underside of the board.
I left the resistor legs very long for two reasons - one I thought I might want to use it for something else if it didn't work well on the board and secondly to avoid over-heating it when soldering (I also used a copper crocodile clip as a heat sink).
Of course, you can also fit a switch between VIN and Enable if you want to turn the thing on and off.