If you have Matlab installed when you install Maple you may receive the prompt to link your installations
this will allow you to use Maple withing Matlab (by replacing the symbolic engine) and Matlab within Maple. If you don't want to connect Maple to Matlab you can leave the box unchecked and hit next.
If you don't receive the option to leave it unchecked and hit next then you are likely running the Maple Toolbox installer, which is only needed for two-way integration with Matlab. To reinstall Maple, please run the Maple installer instead; it should be in your Downloads folder rather than the Maple folder, and it should have a file name that starts with Maple2021, not MapleToolbox2021.