Nothing works… after troubleshooting

hey guys,
i am a beginner and I need your help.

I tried to build a website for our small company. I installed some plugins and a global template but now I cannot reach my website anymore, I cannot edit the pages.

I tried it with Mac Safari, and from another PC with different browsess and but I got always different error messages: 403, 404, Firewall settings etc.

the WP app on my Google Pixel also does not work: I could deactivate some plugins but the other ones I cannot anymore.

Via FTP I have already replaced the .htacces file. I deactivated the plugins which I could. What should I do now? I have to be ready with our homepage until Monday or Tuesday :S:S:S::S:S

Pls help me.

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