Please Help with Syncing 2 Linear Actuators
For your application it would be advisable to use 2 such linear actuators with a dedicated controller and with position feedback for synchronized operation.
Since you have already purchased 2 actuators (without position feedback) and also a separate speed control unit, you would need to carry out the following:

Run both actuators at the same voltage for the same period and check the difference in travel.

Run the faster one through the speed control unit to reduce it's speed to match. Make a mark on this actuator to confirm that that's the one to be used with the speed control unit after final assembly.

Assemble, check for synchronized movement, and fine tune if necessary.

Always ensure that the desk is uniformly loaded.


Here's the schematic.