you don't say which version of Centos you are using. You can use a page manager, os 7, than yum, if 8 the dnf
look like you are doing a manual install from the tar file. the docs say (bash shell):
DOTNET_FILE=dotnet-sdk-6.0.100-linux-x64.tar.gz export DOTNET_ROOT=$(pwd)/.dotnet mkdir -p "$DOTNET_ROOT" && tar zxf "$DOTNET_FILE" -C "$DOTNET_ROOT" export PATH=$PATH:$DOTNET_ROOT
basically you are extracting the files, and adding the folder to the path.
linux does not use .exe, so there should not be one (its windows only). the build will create a folder with all required files in the folder. it will create a <appname> file in the folder with execute permission, that you run via the shell. you can also use dotnet to run the dll.