404 with admin panel on iis php7.2.8

Setup IIS on W2012R2, Php7.2.8, Module rewrite installed, r/w permissions checked

Plain grav installation is working.

As far as I try to use grav-admin there is a 404 error.

Edit: It seemed it’s an problem of rewriting rules. Installed the grav-rtfm-Skeleton I can only reach the landing page but no other page of toc is working withou 404.

What’s to do? There is no hint in online docs.