Create a mysql database :

create database typo3 default character set 'utf8mb4' default collate 'utf8mb4_general_ci';
create user 'typo3'@'localhost' identified by 'typo3';
grant all privileges on typo3.* to 'typo3'@'localhost';
flush privileges;

Install Typo3 and TemplaVoila

composer create-project typo3/cms-base-distribution my-new-project ^9.5
cd my-new-project
composer require templavoilaplus/templavoilaplus friendsoftypo3/typo3db-legacy mehrwert/phpmyadmin
touch public/FIRST_INSTALL

browse http://domain.com/typo3

install, create empty starting page
Template mode, on "Home". Add this to Setup :

page = PAGE
page.10 = USER
page.10.userFunc = Ppi\TemplaVoilaPlus\Controller\FrontendController->main_page
page.10.disableExplosivePreview = 1

List mode, on root page. Add "Website Language" (french, for example)
Page mode, on "Home". Edit page properties. In Resources tab, add this to Page TSConfig :

mod.SHARED {
      defaultLanguageFlag = gb
      defaultLanguageLabel = English
}

Site management > Sites, edit site, add french language (fallback type : fallback on default language)
Filelist mode, on fileadmin : create folder "templates/templavoila".
Upload basic template :

    <!DOCTYPE html>
    <html>
    <body>
    <div id="content">
    </div>
    </body>
    </html>

Page mode, on root page. Add "Storage Folder" folder.
Page mode, on "Home". Edit page properties. On "Resources" tab, set General Record Storage Page.
List mode, on Storage Folder. Add DS and TO. Reference basic template.
TemplaVoilà!+, on Storage Folder. Map root to body, "maindiv" to main div as Page-Content Elements.
Page mode, on "Home". Edit page properties. On "Appearance" tab, set template to Basic for default language.
Problem #1: impossible to set template for other languages : selector is empty.
Page mode, on "Home". Add content for default language. Translate page and content.
Page mode, on "Home". Activate translated content.
Visit the website (http://domain.com/en), content displays fine.
Problem #2 : Visit the website in alternate language (http://domain.com/fr), an error is displayed :

TemplaVoila Plus ERROR:
Couldn't find a Data Structure set for table/row "pages:1".
Please select a Data Structure and Template Object first.

ymauray/procedure.md

Create a mysql database :

Install Typo3 and TemplaVoila

browse http://domain.com/typo3