Sometimes it helps to pause the update for 7 days , but after a few hours resume the update - if this does not help then run the tool to fix problems with the update , but often it is an unknown error
It may take time depending upon your system specs, I recommend to you to wait. For me, installing was stuck at 32% and then eventually progressed to 78%.
If you continue with issue, sign-out and sign-in back and let it be installed again.