Hello Manjit,
It seems that you have chosen the wrong product for the trial.
For Power BI Custom visuals, please use this link ( https://zoomcharts.com/en/microsoft-power-bi-custom-visuals/request-a-trial/ ) and afterwards you will be able to download the custom visuals, which then can be imported into the Power BI reports.
If you haven`t previously used custom visuals, you will be able to find a step-by-step guide on how to import them into the power BI inside the custom visuals folders. look for a file named install.txt
Regards,
Aivis Pavlovs