If you have already started writing a text in Word (or any other text processing programme), some tools can help you to import your references into Zotero.
AnyStyle.io: this tool allows you to copy and paste your references (be careful: each reference must be on a single line), to have them parsed and converted into a format which can then be imported into Zotero. Choose the BibTeX format. The file will be automatically opened into Zotero, or you can open the menu File -> Import, and select the file (with a .bib extension). The references will be placed into a specific anystyle collection. Do not forget to check the references and make some corrections if necessary. It is recommended to split the references you wish to import in groups of maximum 10 references.
Citation Finder searches for citations online, users can then select the right citations and download them. It works well with certain types of documents, such as journal articles, whose references can be easily found online, but is much less efficient for working papers or book chapters. Its great advantage is that it can help to correct potential mistakes in the references of the original document.