Hi there!
There are multiple topics on this:
Search results for ‘slow download category:200’ - Microsoft Flight Simulator Forums
The FAQ also has some suggestions:
Slow download speed – Microsoft Flight Simulator Support (zendesk.com)
If you have been 36 hours at the 45Mbit speed, it’s probably “looping”.
Search results for ‘looping category:200’ - Microsoft Flight Simulator Forums
Looping FAQ:
Download stuck on packages / Install loop & Decompressing issues – Microsoft Flight Simulator Support (zendesk.com)
Depending on your location and ISP: