On this page of your site are outdated instructions and screen captures that are no longer applicable for adding a Robots.txt file.
https://help.sitejet.io/hc/en-us/articles/24275984472855-Add-a-robots-txt-file
For example there is no longer a Media Manager or Redirections option under Menu.
Can you please reply with the instructions to add a Robots.txt file and then update the link above?
I have seen the same issue of outdated instructions and screen captures in various help videos. Also, the screen captures tend to be small and a bit hard to read. Usually, the information provided is good enough to get the idea and then work through the problem on my own. But, the online help should be updated when Sitejet tools and menus change.
Thank you for your feedback. Are you a Sitejet Studio user or use Sitejet as an integration with cPanel or Plesk?
Actually, there is a slight difference from Sitejet Studio to cPanel and Plesk. Those articles are focused on Sitejet Studio mostly, unless we mention otherwise.
Hence the note:
The redirections menu is still under Menu on the left top side.
However, we are in the process of updating articles bit by bit to give more general information - also specific info for features that are different in cPanel and Plesk.
@Karl_Ruser you are absolutely right. We switched our help platform a while back and during that import we ran exactly into this issue. The first steps to improve this are done and I will work on an update of this in the coming months. Due to the extensive nature of our documentation, the update will take a while. 
Do you have a current issue where you need a better screenshot? Are you also a Sitejet Studio user?