Before you do that, try
which -all syms
You might already have the software installed but not licensed. Or possibly you already have it licensed but not installed: command
ver
to test that.
Otherwise:
You do not look like a student, but not wanting to presume:
If you have Student Version of MATLAB then the Symbolic Toolbox is included but is not installed by default. Go into the installer for the Student Version and request its installation.
If you are using the Academic or Professional (commercial) license of MATLAB, then the Symbolic Toolbox is an optional extra-cost. You would then need to go through the appropriate purchasing procedure. You can purchase online at https://www.mathworks.com/store
If you are using an Academic license, it is possible that you are using a Site License that might already include authorization for the software. If so then your IT department should know. (You might also have a site license for a large enough commercial organization.)
