You haven't said which version of RoboHelp you are using. Please always start a thread with this information.
Please go to Help > About and include the full version number. I'm guessing you are on 2022 from the image, hopefully with Update 3 applied. That will show as 2022.3.
I suspect your tutorials were for earlier versions. In 2022 Master Pages became became Topic Layouts. They do the same thing and are described for 2022 at RH2022 Topic Layouts (grainge.org)
In the PDF output Templates are now applied rather than Master Pages. Take a look at RH2022 PDF Templates (grainge.org)
Hope that helps.
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My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.
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