hello ., its a good question
lets go by step
1.Sign in to your My Account page, and choose Install.
2.If you want to install the 32-bit version, on the Install page, in the Install Information section, choose Install.
The 32-bit version works for many of us, but if you want to install the 64-bit version:
Choose Language and install options, choose Additional install options, choose Office (64-bit), and then choose Install.
2. Click Run or the equivalent depending on the browser you're using.
3. when it ask inter your product key and you will be good to go . thanks