Breaking it down:
First sentence: "Click the “Download” button to begin the download process. Once the download is complete, the installer will begin installing the selected applications and components."
"allows you to choose" could be "enables you to select|permits you to pick|lets you decide".
First, the main instruction is to swap terms with three options each. The example they provided shows replacing words with three synonyms in curly braces. I need to identify all such terms in the given text. Let me go through each sentence.