Give it a try

Intro

This implementation uses a custom table, UC_PDF_CUSTOM_FILES, to store the documents. The first implementation does not have the version column. The second implementation uses a version. When a custom table is used, the VERSION column is optional, and PDF Region Pro increments the version column only when it's provided in the Version Column attribute.

In SQL Workshop \ SQL Scripts \ Quick SQL enter: 

uc_pdf_custom_files
  doc file
  doc_owner 
  version_number

# settings = { PK: "TRIG", language: "EN", APEX: true }

Which generates: 

-- create tables
    create table uc_pdf_custom_files (
        id                             number not null constraint uc_pdf_custom_files_id_pk primary key,
        doc                            blob,
        doc_filename                   varchar2(512),
        doc_mimetype                   varchar2(512),
        doc_charset                    varchar2(512),
        doc_lastupd                    date,
        doc_owner                      varchar2(4000),
        version_number                 number
    )
    ;

    -- triggers
    create or replace trigger uc_pdf_custom_files_biu
        before insert or update 
        on uc_pdf_custom_files
        for each row
    begin
        if :new.id is null then
            :new.id := to_number(sys_guid(), 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX');
        end if;
    end uc_pdf_custom_files_biu;
    /

Check also

When you need to dynamically generate a document's primary key value or describe a document by more than one primary key value, PDF Region Pro supports using a custom PL/SQL function returning a new primary key. See the Custom Table (Custom PK) example.

Demo without version column

Demo with version column