Sorry late reply. (in ld player or rooted android) playstore auto login needs activated.
1A: patch apk signature verification using luck patcher (vids is some platin mod post andyoutube)
OR 1B: skip to step 2 is u don't want to use luckypatcher (I haven't tested this method)>>>
2: install titanium backup pro (& give root permission) and the original game from playstore
3: Login to ij2m
4: in menu>> preferences of titanium backup find backup external app data and set to always.
5: make backup of ij2m from titanium backup
6A: if unsigned method used install mod apk over original (sud work). and try to see if login works.
6B: uninstall game (make backup of obb of game) and install mod apk and restore obb to proper location. (play login will not directly work in this case)
7: if login for 6A did not work or if using signed mod.... restore"DATA ONLY" from titanium backup pro.
8: Enjoy game. (works most times, use at ur own risk, if does not work uninstall app and tryfrom step 2 again. )