I have licence version of Office 365 E3 and Dropbox Advanced Business Version (Feature in SSO). I want to use in Single sign on Feature in my current site. When integration between Dropbox to SharePoint Online (Office 365) with SSO. Than next step to create X.509 certificate (A .pem file security certificate supplied by your identity provider) and upload file in particular area. So that how to create X.509 Certificate in 0365 Online or any other way to likes to purchased any other tool (to create X.509 Certificate for O365 online site not OnPrimeses Site likes SharePoint 2010/2013/2016). Please suggest me.
Note :- I want to implement O365 online site not in OnPrimses Version of SharePoint and in which types of Step to implements in O365 online site.