Grav installation on 1&1 IONOS

EDIT: I just discovered that this error is appeared too when trying in local with apache2, but with XAMPP on Windows It’s working…

Hello!
I just tried to add Grav to my host (transfert the zip file with FTP and then unzip it with SSH), but it’s not seems to be working.
I extracted grav-admin in the root folder, and when I access my website with

https://mywebsite.com/grav-admin

it redirect me to

https://mywebsite.com/grav-admin/admin and then

Error 404

I tried to edit .htaccess by uncommenting RewriteBase / but not working either…

Am I doing something wrong?
Thanks for any answers!