WAAD as Claims provider trust

Hello,

I have a onprem version of ADFS3.0 running with SP2013, also onprem version. I have configured ADFS for authencation with Office 365 and this works perfectly.

I need a few thousand users to logon to SP2013, but I don't want them in my local Active Directory because of the license costs.

Can I configure the Free version of WAAD, put the users in there and allow them to authenticate via my ADFS3.0 setup onprem? I think I need to add the WAAD as "Claims Provider Trust" but I don't know if this can be done or not.

Hope anyone can help me.

Kind regards,
Stefan