The insaller is not updated for version5

[ullas]

The installer document is not yet updated to be used. It still refers to old versions. It should be modified as
"require": {

    "ypnos-web/cakephp-datatables" : "dev-master"
   
}

[umer936]

My fork https://github.com/umer936/cakephp-datatables/ works for CakePHP 5
https://packagist.org/packages/umer936/cakephp-datatables

"umer936/cakephp-datatables" : "@stable"