Cannot view pdf file embeded in web pagein task module on desktop

We have website host documents in pdf format. we want be able to view the pdf files from Teams Task Module. 

We want to have a link in the chat, and when user click the chat, will bring up task module, and retrieve the web page and display the pdf file.

The link works fine in iPhone and iPad.

But in desktop, either in Mac, or Windows, the page loaded, but cannot view the pdf. 

either via Microsoft Teams via Desktop or via webapp.