Is this means that I CANNOT use my Global Pass in another schedule? Means that I have to pay for another train ticket if i choose  another time?

If you have a global pass, you can use it for all these trains.

I'm not sure why that remark is showing up for an international train: it's clear that you can't use a one country pass there.

This screen shows the SuperFast trains, (AVE in ESpana, TGV in FRance), and these indeed all have a hefty SUPPLement to pay-for the REServation and the surcharge for that hi-speed. Its a common trap that all EUrail newbees fall into-seemingly. Plus that in fact if you choose it, there will be a next message it cannot be done online but go to counter. This is for ALL INternational such trips in/out of FR.

You can-it has been posted here by now a few dozen times, use local/regional trains, that means more changes and longer time spent in transit. Then its ´free´=no additional cost. As most from the USA seem utmost frightened at that perspective and the sheer idea of having to spend more minutes as necessary, its often neglected.

This is-again-how it goes then: in Barca take the local Rodalies Regional Express-stops in Sants=main but also some other underground stations to Cerbere, ev 2 hrs, along the coast with nice views, but a very basic trainset with just plastic seats. Cb is the first stop in FR just over border. Here you have to change trains all the time, as ES has broad gauge and FR the normal standard gauge. From there use local SNCF TER trains-find them on ter.sncf (region Occitanie) or all are also on the pan-EUR site bahn.de (of german rails-keep that in mind, it can serve you for nearly all of EUR, except ESpana).

Now Carc is a rather roundabout route by train, its near the end of a branch line from Toulouse. You can-but have to pay 2-3€ for the bus, perhaps get there faster by bus from a town called Beziers.

Again: IN ESpana nearly all trains require a REServacion, to be done at counter and pay extra. Except happy for you these rodalies locals. You need to pass gates in Barca-show pass on fone to attendant and she will open 1 for you. In FR you have to pay 10 or 20€ for INland TGV but a lot more for TGV over the border-for further plans. You can get the lower rate by using TGV only till last stop before border. Or use the slower regional trains, named TER-for free.

Once again, whilst I now sit in an ES-airport: RENFE/ES is by far the very worst of railsystems for Passholders, followed by SNCF/FR, then Tr.It in ITaly. Once you have conquered that, the rest is a breeze. Those 33 EUropean countries all have their very own style of running trains and annoying people. Thats the charm of foreign travel: to encounter such funny ways of doing things!