You need to download this suite:
ReaPlugs VST FX Suite
Here is the description from the reaper website:
Want to use some of the comprehensive FX plug-ins that REAPER provides, but stuck in another host? Haven't made the switch yet? Fear not -- you can download ReaPlugs, a package of FX that includes many of the plug-ins that come with REAPER, for free!
So these plugins are in vst2 versions and should work well with ALK.
Maybe the plugins you are talking about are not in vst2 format yet or you have to download them first in vst2 using the link I provided.