Hybrid self-service site creation redirects the default self-service site creation page in SharePoint Server (/_layouts/15/scsignup.aspx) to the SharePoint Online Group Creation page. By configuring this feature, you can help your users to create their sites in SharePoint Online instead of SharePoint Server.
Hybrid self-service site creation respects your hybrid audience settings. If you use a hybrid audience, members of the hybrid audience will be redirected to SharePoint Online for self-service site creation, while on-premises only users will continue to be directed to self-service site creation in SharePoint Server.
This setting can be configured independently for each web application in your farm.
Hybrid self-service site creation is available in SharePoint Server 2013 with the March 2017 PU.
Configure hybrid self-service site creation using the Hybrid Picker
Configuring hybrid self-service site creation is done by using the hybrid picker in the SharePoint Online admin center.
Note: If you've previously configured other hybrid features with the hybrid picker, you can go directly to the SharePoint Central Administration website to manage hybrid self-service site creation. In this case, the hybrid connection has been made and there's no need to run the hybrid picker again.
Log on to a server in your SharePoint Server farm as the farm administrator.
From your SharePoint Server computer, open a web browser and log on to Office 365 as a global administrator.
In the SharePoint Online Admin Center, click configure hybrid.
On the hybrid picker page, click Hybrid Picker.
Follow the wizard and choose Hybrid self-service site creation when prompted.
When prompted, choose the web application with which you want to use hybrid self-service site creation.
When the hybrid picker wizard completes, hybrid self-service site creation will be enabled for the web application that you selected.
Manage hybrid self-service site creation
Once you have configured hybrid self-service site creation, you can manage it in the SharePoint Central Administration website.To manage hybrid self-service site creation
In Central Administration, click Application Management.
On the Application Management page, under Site Collections, click Configure self-service site creation.
In the Web Application section, select the web application where you want to manage hybrid self-service site creation, and then select or clear the Create Site Collections in SharePoint Online check box.
Note: While hybrid users of this web application will be redirected to SharePoint Online for self-service site creation, the other settings on this page continue to apply to any on-premises only users.