In order to be able to upgrade your UMi Plus to Android 7.0 via FOTA method (Wireless update), you have to have this latest Android 6.0 version installed on your device. http://community.umidigi.com/thread-5840-1-1.html
Sorry but the Android 7.0 OTA update zip file won't be available for manual update, at least not the current version. You can wait for the wireless method or flash your phone with SP Flash Tool.
As Ben mentioned there will be not available OTA zip file for this Android 7.0 release.
If you are really interested and mad about Android 7.0 update please request for update manual.
Please go to thus thread and follow instruction. http://community.umidigi.com/for ... a=page%3D1#pid35076