It's a fairly complex network of routes leading to Fátima, and the majority of them are not at all waymarked, and therefore involve a lot of DIY-imposed tarmac. And rough sleeping / camping / hotels etc.
And almost no parts of the Fátima routes from Spain are waymarked in the slightest, the only proper exceptions I know of being the Huelva > Faro and the Mérida > Badajos (and IIRC > Elvas) routes, the latter actually being a portion of the Fátima Way from Madrid or via Ciudad Real from anywhere between Cartagena and Valencia. Plus some unrelated hiking/cycling routes that are de facto parts of a Fátima Way.
And there are four or five routes just within Portugal that are officially recognised, but waymarked not at all, except for some road signs on tarmac for walkers, cyclists, and drivers alike pointing to the Sanctuary.
The Portuguese Tourism Ministry has however started a programme of some more systematic waymarking of the more "important" routes to Fátima, so that things are improving.
That is actually rather variable. When I was there in August last year, letting me stay just a second night was very much by exception. They can get quite full with large groups in high pilgrim season, I believe.