https://github.com/emard/ulx3s/blob/master/doc/MANUAL.md#precompiled-opensource-tools-for-all-platforms here is described how to download nightly ready-compiled binaries
These works better :-) Bitstream generation was successfull, next step will be loading it to the board. But one question: What should I enter for the 85K version on the next-pnr command? Do I need to change it from the default 45K in the blinky Makefile?