Hello, Ahmed SAbbour,
Thank you for your response.
1/ About permissions issue:
Could you please, check if the user you use has administrator permissions or maybe superadmin.
Check how it works with disabling all 3rd party plugins that are not bundled with our theme.
If you have some restrictions made by your server, please, check it by contacting your hosting provider.
2/ Ajax adding for variation of a variable product is only possible if it is used in conjunction with swatches https://youtu.be/LgzC4iK-j6A. That is, this attribute is a swatch + the swatches shown in the element ( https://prnt.sc/GBzg116DCLoE ). Only in this case will swatches scripts do their job and make it possible to add without page reloading.
We hope this information is helpful.
Kind Regards,
8theme team