Checked out Hornbach for products that look right and found;
* Base paper PROTEGO YEP 2500 15x0.20m - TEmballage
Used as an insulating layer between the foundation and the sill. Polymer bitumen (PmB).
Foundation insulating paper is an elastic, nailable sealing layer built on a strong polyester felt with high tear resistance that is coated with SBS-polymerized bitumen. The top and bottom sides are sanded.
It sounds right.