The updated version of Guto Pro comes with a theme (zip file). So, firstly, you need to visit https://gutotheme.com/my-account/downloads/.
You will see a download button right beside it. Once you have downloaded the updated theme, do the following steps to install Guto Pro successfully.
You can fix the issue yourself. Probably, the updated theme is conflicting with the previous Guto Pro Toolkit plugin. Try deleting the old Guto Pro Toolkit plugin before activating the updated theme. Then install the updated Guto Pro Toolkit plugin from Appearance > Install Plugins.