Hello,
We do not require your formal acceptance of the license terms.
If you are registered and logged in, the MSigDB gene sets can be downloaded from here:
https://www.gsea-msigdb.org/gsea/downloads.jsp.
If are not logged in, you will be taken to a Login page, where you can enter the email address you registered with.
If that does not allow you to access the page, try registering again by clicking on the blue "Click here" to register link near the top of the Login page.
If that still doesn't work, let us know exactly what you see.