To help with issues you might encounter when installing Office because of slow speeds or unreliable connections, as a first step download the Microsoft Support and Recovery Assistant.
If the Microsoft Support and Recovery Assistant didn't help, follow the steps below that are specific to your plan. You need to be connected to the internet to download this installer file, but once that's done, you can then install Office offline on a PC at your convenience.
The steps below differ if your Office product is part of an Office for home or Office for business plan so you need to select the correct tab for your product.
Office 365 Home
Office 365 Personal
Office 365 University
Office Home & Student
Office Home & Business
Office Professional