YES this is correct...
Power supply feeding motherboard connects to laser board & powers both boards incl laser.
The motherboard will have a laser output of 3 connections + / - / Sig.
The laser board will also have matching pins - or a + & -, & the signal goes to TTL+ depending what laser board you have.
Ideally your laser board will have the button for low light output for outline, & will have the dedicated 3 pin input.
I use a long 3 way Dupont cable cor this off ebay for very little.
Couple both boards together via matching connection points - ensuring the correct wire goes to the right place, or you will likely cook both boards AND the laser.