Mozarabe from Granada to Merida will not be busy even during Holy Week.
I walked without a map, or guide and was lucky to meet a local in Cordoba who had walked the year before. There are no pilgrims albergues, but there are church run night shelter albergues where you can stay if you have your credential (or, not if you're as desperate as I have been a couple of times!).
The accommodation can be anything. The best advice I was given was to ask at Policia Local, or a local bar if no police station.
You can of course simply stay in pensions, hostals, or hotels. But, a true, hardcore pilgrim like myself wanted to do it properly. However, I ended up sleeping outside more than once.
There is one tough stretch of almost 40KM on Mozarabe between stays. Plenty of safe, and very beautiful 'wild' camping, but no water supplies. It's a winding, up and down stretch, but well worth the walk. If you decide to camp take plenty of water just in case it gets hot - it can do at the end of March. Mind you, it can also drop well below freezing by night.