From the README note you gave along with the template
Steps to install WHMCS Template
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1. Upload the [“EcoHostingV1” or “EcoHostingV2” or “EcoHostingV3”] folder to your WHMCS Folder /templates
2. Activate [“EcoHostingV1” or “EcoHostingV2” or “EcoHostingV3”] Template from WHMCS Admin Panel Setup
3. Refresh the Client Area
Notes
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1. Upload the [“EcoHostingV1”] folder to your WHMCS Folder /templates
2. Activate [“EcoHostingV1” ] Template from WHMCS Admin Panel Setup
3. Refresh the Client Area
These are the steps i followed without uploading your whmcs template since i already have whmcs downloaded with admin and licence included. But when i activate it on my admin panel in step 2 and refresh the client side step3 , i have a blank page.