Can you please confirm you followed these steps?
Your download will contain a zip file that contains the software (ex4 extension) in a compressed format. Please note that dll imports in the MetaTrader 4 terminal have to be enabled for SphereTester to operate correctly.
Download the zip file and open it
Right click on the ex4 file and select copy
Open your MT4 Terminal and go to File/Open Data Folder
Go to MQL4/Experts, right click and select paste
Restart MT4 and SphereTester will be available in the Strategy Tester
Select SphereTester and click on start
Enter your licence key when prompted