the tutorial has no idea that you don't have the scenery for that area... there's no way for it to tell... to fix the problem, enable TerraSync and spawn in at that airport... the scenery will download and you'll be good to go then... the main thing is to enable TerraSync so your system will download the necessary scenery...
the default airport for 2017.3 is LEBL which is Barcelona–El Prat... Sabadell* is LELL... they're about 20km (12mi) apart... the tutorials for the 2017.3 release were split between the two airports because some things are easier/better done at one then the other... there was a question about larger commercial craft being able to spawn there and actually be able to take off or land... the c172p team decided to split their tutorials between the two airports... at that time, they were fixing up the tutorials and flights for each default airport as they were chosen... that's a lot of work so now it isn't done like that... take, for example, a scenic flight tour... someone has to actually go fly that and write everything down so it can be put into the tutorial so that you can come along and actually follow it and fly the same tour...
the new upcoming release of FG (currently in RC status) has PHNL in Honolulu as the default airport... the c172p will take you from PHNL to LEBL and LELL when you run its tutorials so folks will still need to downloaded the scenery... it is just a tutorial, after all... they can be done pretty much anywhere... the question is about maintaining and recoding them when the default airport changes... the team decided to get the tutorials done, have them well detailed, and then to just leave them as is until such time as they must be changed for some reason... it would be rather more confusing for the tutorial to tell you to start your engine and then taxi to the left down the taxiway and turn right onto the runway when the airport parking you may really be in has the taxiway going straight out in front of you and the runway on the left
so, remember... each craft may have its own tutorials... some do not... the tutorials may be written for some airport that you may not have ever been to... when you start them, you will transport to the new location... if you don't have the scenery already, just wait for it to come down the pipe and then start the tutorial again...
BTW: welcome to FlightGear! we're glad to have you come aboard
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."