Getting assets into source builds?

How you guys add assets from market place into project that is run on source built engine?

I see import options only for prebuilt engines in epic launcher, but, for source built engine it says asset is not compatible.
There must be some way to import market place assets into source built engine?

based on my experience No there is not . i remember installing binary engine just to get some content packs

Thank you for input! Just the fact that somebody gave a reply is of more worth than not being able to import assets! sorry but just found this one while exploring github randomly .Not tested by me.