A good description for the assembly of the arcol.hu 3.0 can be found here.
Because the 4.0 design is only a bit different you can follow all steps until you are at this state:
After the assembly of the nozzle/heater/thermistor-block with fire zement you have almost done it.
The next step is to insert the short PTFE-tube inside the heatsink block like this:
Maybe you should take a look at the winding inside the heatsink and remove residues which might block the nozzle.
Then you screw the stainless steel connection tube inside the heatsink block.
You can use a wrench or pliers to be sure it is firmly mounted.
At the other side you insert a grub screw.
To fix the PTFE-tube inside put the grub screw on top into the heatsink using a screw driver.
Then you can fix the whole construct inside the slot of the wooden extruder connector.
The wood is 5 mm thick. The slot inside the heatsink is a little bit smaller (4.7 mm) so that one has to use pliers or a vice to fix the heatsink inside.
This ensures a firm grip.
The filament hole has to be in one row with the connection holes in the wood-clamp.
Finally you screw the previous assembled nozzle/heater/thermistor-block onto the heatsink and put thermoresistant isolation around the wiring of the hotend.
Be sure the hotend is screwed on tight:
It looks like this, if you screwed it into to loose:
The steel-bolt has to cut the winding into the bottom of the nozzle. Use a wrench for doing this.
The two holes on top of the woodplate have a distance of 50 mm. This fits exactly into the holes of the wades extruder used to connect it to the x-carriage.
You can insert the inlay and clamp the Wades extruder onto the hotend or widen the hole for the inlay until you can put the upper part of the heatsink into the extruder.
After this you are free to connect the wires with the plug as described at the end of the arcol 3.0 assembly.
Have fun printing with these excellent hotends!