I would recommend you to install it via Chum. You probably need to install OSM Scout Server for offline tiles and routing too. Pure Maps and OSM Scout Server are both created by Rinigus and available from Chum.
Chum is an additional repository, which build the SFOS apps from source. There is even a GUI App available, where you can easily install apps (like the Jolla Store). More information about Chum.
For hiking there is also the Map App OSM Scout created by Karry ( OSM Scout is a different app besides OSM Scout Server)