Installing Autodesk software and it requires Internet Explorer 10 (or higher) to run. I have IE9.
I can find installers for IE 11 and even IE 9 on the microsoft site but not 10.
I don't know if IE11 will cause other problems since I am also running some old software
Any ideas?
Microsoft maintains good backward compatibility. So your other old software should not break.
Even if it did, IE has a feature called Compatibility Mode, which lets you run it as past versions. You could put IE 11 in Compatibility Mode for 10, 9, 8, 7, 6, or 5.