Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I suspect that either you have an available-space-for-the-download onto your phone issue... no space available to put it simply... or else, something is wrong with the source for the download and your phone is refusing to complete the download as a result. (Which can happen if your phone's anti-virus program detects a virus or other infective problem code in the download.)
First, check available space on the phone.
Second, delete Temporary Internet Files and Temporary Files using Disk Cleanup.
Third, restart your phone - only after that process is quite complete.
Fourth, what is the Windows version on your Microsoft phone ? as revealed by
Control Panel - System and Security - System
(It suddenly occurs to me also: your intended download may be for the wrong OS or the wrong version... doubtfully, but possibly.)
Let me know please. Thanks.