obviously without the full error its impossible to say for sure. But double check your php and make sure that you’re not referenceing https://fenisecleaningservice.rf.gd/?i=1 specifically
but that mistake caused me a lot of errors when I changed to a .pp.ua domain lol
I had a quick look at your website, and I see that there is an index.php file from WordPress.
And nothing else. All other WordPress core files are missing, as well as any configuration, plugins, themes and everything else needed for a WordPress website to work.
If you want to switch from your free subdomain to your .com domain, please see this guide: