Occasionally your browser settings may impact how the system behaves. We can not control these setting are they are as individual as you, we can simply offer up some options to help make everything work.
Below is a list of known settings:
Training PDF downloading rather than opening in window – FireFox
Open Firefox and Go to the small hamburger menu on the top right hand side
Click on Options
On the General Settings – Go to Files and Applications
Find PDF on the list and used the drop down list for ACTION and changed to Preview in FireFox.