First, download the Davinci Resolve 20
Then, install it with
chmod +x DaVinci_Resolve_*.run
sudo SKIP_PACKAGE_CHECK=1 ./DaVinci_Resolve_*.run
To fix Davinci Resolve not starting
cd /opt/resolve/libs
sudo rm -rf libgio-2.0.so libgio-2.0.so.0 libgio-2.0.so.0.6800.4 libglib-2.0.so libglib-2.0.so.0 libglib-2.0.so.0.6800.4 libgmodule-2.0.so libgmodule-2.0.so.0 libgmodule-2.0.so.0.6800.4