You have to download each file individually. Here are the steps:
a) At https://support.broadcom.com, login and click on Enterprise Software.
b) Then click on Product Downloads.
c) In the search field, type: unified (to filter by the product name), then click on Unified Infrastructure Management.
d) Select Release 20.3 in one of the product listed in your browser, in the screenshot below there are a few examples of the product name listed. Then click on the product name, do not click on the download button.
e) Then click on the Cloud button to download the file individually.