I have downloaded Ventura on my MacPro.

Apple menu -> System Preferences or Settings -> Displays. Choose a higher resolution for display. That will mean smaller text. You can adjust it after the installation is complete. If the option. is not available, Quit the installer by hitting command-Q and then adjust it before running the installer.

If you have a mouse with a scroll wheel, use the scroll wheel to see if it lets you scroll through the agreement. If you don't, click on the text of the agreement, and hit shift-down arrow until you select the end of the agreement. It sounds like your display is currently set for too low a resolution to view the entire agreement. This means it will try to show it beyond the edge of the bottom of the txt for you to read. Once you reach the bottom of the text, agreeing is possible.