It's clear from documentation on how to declate 'PL/SQL Table' at runtime
(DeclareVariable + DimPLSQLTable.) but i don't see any guide on how to declare simple array variable at runtime for Array DML...
I'm using DOA 4.1

You mean at design-time? The variable editor form has a "PL/SQL Table" checkbox and a table size and string size property.

no, i mean 'PL/SQL Table' vs 'Array DML' variable

PL/SQL Tables and Array DML are unrelated.

Array DML cannot be declared at design-time. It requires that you pass a variant array for each variable of the query. The variables are declared as usual.