The library used by IAR nmsis dsp examples located in $PROJ_DIR$\..\library\prebuilt\libnmsis_dsp_rv32imafdc.a,so you should:
Click nmsis_library.eww, build the library.(the generated library with .a suffix is placed in Your path\NMSIS\NMSIS\ideprojects\iar\library\Debug\Exe called nmsis_dsp.a, and nmsis_nn.a, which is respectively ready for the nmsis_dsp_examples and nmsis_nn_examples projects.)
Create a directory called "prebuilt" in Your path\NMSIS\NMSIS\ideprojects\iar\library
Copy and rename _nmsisdsp.a to _libnmsis_dsprv32imafdc.a, put it in the Your path\NMSIS\NMSIS\ideprojects\iar\library\prebuilt
Firstly, I clone respository according https://github.com/Nuclei-Software/NMSIS/blob/master/NMSIS/ideprojects/iar/README.md, but when open nmsis_dsp_examples.eww by IAR IDE, then build the examples,it fails: