Your instructions [1] say to use: "nischayn22/mediawiki-api"
in addition to the main code, however your project page on github is defined as: "mediawiki_api"
[2]. Can you confirm that the instructions contain a typo or clarify what the deal is. Thanks!
Topic on Extension talk:Sync
You need to use "nischayn22/mediawiki-api" in composer. Its the composer name for the same library.