No implementation found for java.lang.String org.ebookdroid.droids.mupdf.codec.MuPdfDocument.getFzVersion() (tried Java_org_ebookdroid_droids_mupdf_codec_MuPdfDocument_getFzVersion and Java_org_ebookdroid_droids_mupdf_codec_MuPdfDocument_getFzVersion__) - is the library loaded, e.g. System.loadLibrary?

[foobnix]

you should build mupdf at first

cd Builder ./link_to_mupdf_x.x.x.sh (Change the paths to mupdf and jniLibs folders)