Ok four times I’ve traveled to and from these stations. And they are long and boring to get to and at first I though I’d cocked up the deal. But as I sit here I’ve got the biowaste in the hold and a can’t unload it to seal the deal. Sod this.
There are plenty of guides and tutorials out there to show you how to carry out a mission, just make sure they are not too old as the game mechanics changed over time.
Here, for example, is a video I made of a delivery mission, not got a polished presentation style but it shows how to do it:
BTW - if you see the destination station is a long distance from arrival (it is shown in the mission description) - don't take the mission if you don't want to spend the time travelling.