This question already has an answer here:
The ACM license states
(iii) Post the Accepted Version of the Work on (1) the Author's home page, (2) the Owner's institutional repository, (3) any repository legally mandated by an agency funding the research on which the Work is based, and (4) any non-commercial repository or aggregation that does not duplicate ACM tables of contents, i.e., whose patterns of links do not substantially duplicate an ACM-copyrighted volume or issue. Non-commercial repositories are here understood as repositories owned by non-profit organizations that do not charge a fee for accessing deposited articles and that do not sell advertising or otherwise profit from serving articles.
Does this (somehow) include ResearchGate?