Step #1 in the One Day Morrowind Modernization: Land & Landmass Additions list
PT_Data.bsa file needs to be used, even if you're not using other province mods! See the CFG Generator preset for the mod list you're following for an example of the correct BSA loadout.
There are two versions; one that contains HD textures and assets, and one that retains a more vanilla look for lower end systems (or folks who want that look).
It contains two
.bsa files that must be registered:
TR_Data.bsa. Please see the register BSAs tips page for more information.