Categories not accessible by the sidebar menu

I am new to WordPress. 2 questions.

1. I cannot access the categories posts by using the list of categories in the sidebar menu. It gives me a 404 and this URL address https://taraquebec.org/Wordpresscategory/analyses/analyses-environmentales/ when it should produce https://taraquebec.org/Wordpress/category/analyses/analyses-environmentales/ which functions well. All my program files are in the directory /Wordpress/ Is it because I am using the “Template extreme” theme ?

2. Is there a way to have accentuated letter(french) inside the program code ?

Thanks.

Nitram9