If you have paid support, you can download "recent" old versions. Otherwise, only the latest. There is rarely, if ever, a need for an older compiler. (And this is the Fortran forum, not C++.)
19.0 is no longer supported. As Steve said, you probably can use a newer compiler. The ABI has not changed for many years. If you still think or can offer some proof that you absolutely have to have a 19.0 compiler AND you have an active Premier Support entitelment, you can open an issue on Online Service Center and request an older package (within some limits).