what does this mean please?
Whoops \ Exception \ ErrorException (E_COMPILE_ERROR)
Declaration of Doctrine\DBAL\Driver\PDOConnection::query() must be compatible with PDO::query(string $query, ?int $fetchMode = null, mixed …$fetchModeArgs): PDOStatement|false
It means that wherever you have query defined needs to take the first parameter like it’s parent. The full error output should tell you in which file that needs to happen.
Are you trying to install concrete5 version 8 on PHP 8?
If so, that’s the problem: only ConcreteCMS version 9 is compatible with PHP 8: concrete5 v8 can run on PHP from 5.5 to 7.4.