set cookies with "Same site" to "None" instead of "Lax"
Currently, CubicWeb set cookies with the "Lax" policy for the "Same site" attribute. This attribute does not allow using cookies from another base URL. The "None" value let other site to use CubicWeb cookies. This is necessary to test RQLIO from a local dev server.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information