Ecommerce themes wont show as displayed

People i need help with my e-commerce site that i am building the problem is that when i apply a theme there is no banner image slider and just a blank weird page
the only working theme i found was Shop-isle (that i am using right now) which is sweet but very very slow and its site speed is pretty bad please help me install and customise a theme properly i have attached screenshots of when i try any other theme
Screen shots:
how the theme should be:
https://ibb.co/t3RPZKz

when install and click live preview:
https://ibb.co/R6jJvmm

Also tried setting homepage to shop:
https://ibb.co/D5ZdnWv

The page I need help with: [log in to see the link]