SpreadTrum USB Android driver


Hello list
A friend obtained a Mobicel Android phone and installed the Accessibility
suite which works fine. The Win10 pc does not "see" the phone when plugged
into the USB port. We switched permissions etc. on. The support people says
we need SpreadTrum USB drivers. I did a google search and downloaded the
driver from 3 different sites but twice I got a "not digitally signed"
message and the third install just says there were errors. Does anyone know
about this driver and if so, where could I obtaine one which will install?