Hi and thanks for reaching out! I'm an Independent Advisor and a Microsoft user like you. Please allow me to assist with your issue.
The disc version of MSFS 2020 is supported by Aerosoft. In your case, you might have a faulty disc. Therefore, please contact their customer service for help in obtaining a replacement.
General FAQ: https://helpdesk.aerosoft.com/portal/kb/article...
Create Ticket: https://helpdesk.aerosoft.com/portal/newticket
Alternative, there should also be a download key that came with the boxed version which can be used to download MSFS 2020 from Microsoft Store. So you won't need to install from the disc. https://helpdesk.aerosoft.com/portal/kb/article...
Please let me know if I can help you further!
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.