Hi. My name is Ivan, and I am an Independent Advisor. I'd be more than happy to assist you. I'm so sorry that you are experiencing this issue. My working hours vary & I usually reply between 09:00am & 6:00pm Monday to Sunday - (GMT-5).
The first thing I'm going to do is turn off my PC and turn it back on with the installation pendrive in place and proceed to turn off the PC and turn it back on.
Here you will have to start the Windows installation. Now press the shift + f10 keys. This will open CMD and here you will write diskpart and press enter.
type List and press enter and once this is done type Select Disk 1 or select disk 0 in the case of having two disks in the unit then type clean to clean the selected disk and it will indicate the disk was successfully cleaned now type convert mbr and it will indicate diskpart successfully converted the selected disk to the mbr format Close the console and with this the problem would be solved.
you can watch the following video for additional help https://www.youtube.com/watch?v=hL0EAYpNRgA