These files are needed to extend online map providers in Locus Maps. providers.xml is the essential one. Icons are just for decoration.
Copy providers.xml and all icons into the directory:
"...\Locus\mapsOnline\custom"
Go to Google Play, install and run Locus Map Tweak:
https://play.google.com/store/apps/details?id=com.mjk.locusmaptweak
Find or fix maps with this method:
http://docs.locusmap.eu/doku.php?id=manual:custom_online_maps
Google+ Page:
https://plus.google.com/105415797711448238292/