The HD5450 is obsolete and considered to be Legacy and not supported by AMD drivers anymore since 2016.
So there are no Windows 11 drivers for your Legacy GPU card: https://www.amd.com/en/support/graphics/amd-radeon-hd/ati-radeon-hd-5000-series/ati-radeon-hd-5450
If the Windows 10 AMD Drivers doesn't work in Windows 11 then you have two other decisions to make.
Only chose you have is to install Windows 10 and see if those drivers will still work with the latest Windows 10 version or not.
Otherwise you will need to upgrade your GPU card to one that is still supported. At the moment, All RX Series GPU cards are supported.