How to download and setup standard-edition
Open terminal and run command
                                            git clone https://github.com/contao/standard-edition.git
                                        
                                        git clone is used to create a copy or clone of standard-edition repositories.
                                        You pass git clone a repository URL. it supports a few different network protocols and corresponding URL formats.
Also you may download zip file with standard-edition https://github.com/contao/standard-edition/archive/master.zip
Or simply clone standard-edition with SSH
                                            [email protected]:contao/standard-edition.git                                    
                                    If you have some problems with standard-edition
You may open issue on standard-edition support forum (system) here: https://github.com/contao/standard-edition/issuesSimilar to standard-edition repositories
Here you may see standard-edition alternatives and analogs
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