If you need to get the complete text of a publication of which you already have the bibliographic details (author(s), article title, journal title), searching and locating seems easy. Indeed it is, but only if you use the right information source!
Sometimes people try to find a journal article in the library catalogue, but fail because they type words of the journal article in the search box. Journal articles are rarely described in library catalogues, because in general this type of database describes the library collection on the level of book titles and journal titles.
So to do this search correctly, you should type words of the journal title in the search box to locate the journal in the library collection and search in the (digital) journal itself to locate the wanted article. Another option is to choose a bibliographic database and search for the article title.