The more platforms that you publish your research on, the more exposure you should receive. SSRN is more of a repository and does note allow for much interaction like RG, but will give your research more exposure. Academia is another platform that is very similar to RG.
SSRN (Social Science Research Network) is a platform that serves as a repository for preprints, working papers in social sciences and humanities. It is currently owned by Elsevier (and in fact Elsevier journals propose to upload submitted papers as pre-prints in SSRN). While pre-prints on SSRN can receive some visibility, please consider that they are not peer-reviewed (and thus barely cited). For most academic journals, posting preprints on SSRN is not considered prior publication, but some journals require to delete pre-prints after acceptance.
Just a couple of weeks ago (21 September 2021) Scopus (Elsevier) announced that SSRN pre-prints are included in their database, and this can give more visibility to papers on SSRN that are already indexed on Google Scholar.
SSRN, as mentioned by the respective colleagues, is a preprint repository. It does, however, post accepted papers. In my experience, some journals where my articles were published posted the articles on SSRN. That is how I learned about this research repository. The author’s copyright is not transferred when the article is posted on the repository. It further broadens the public display and dissemination of scholarly research across a wide range of fields. Google Scholar recognizes the papers posted on SSRN.