rests

There is only a free version. There is no paid-for or special or enhanced or unrestricted version.

The quarter-note rest that you see is just an icon representing rests in general. If you click on it and then click on an icon of a note of a certain duration then when you click on the score it will place a rest of that duration. Click on the rest icon again to toggle rests OFF.

Try entering notes and rests using the computer keyboard, though, and you might find it quicker. See the Handbook for details:
https://musescore.org/en/handbook/4/entering-notes-and-rests