No SSL after page transfer

I made a website for the client. In my account, the site had HTTPS. After the transfer to the client’s account, the website no longer has SSL and is HTTP. With the website, I transferred the premium plan and domain (last friday). I do not know what is causing. I do not have any html elements on the page. I checked everything with wix instructions in wix support. Help me please

You are best suited going to Wix Support and asking them.
https://support.wix.com/en/article/contacting-wix-support