I checked RichMemo with Laz trunk/fpc 3.2.0 and Laz 2.0.10/fpc 3.2.0 and found some issues in the package - I fixed them in the current ccr revision 7537 (I hope the package maintainer does not mind me modifying his work, but I thought it's faster this way).
Please try again with the latest ccr revision. Note that RichMemo has been split into a runtime and designtime package some time ago. The runtime package is "richmemopackage.lpk", the designtime package is in folder "ide" and named "richmemo_design.lpk". You must first load the runtime package, try to compile it - it should work; if not click "More" > "Recompile Clean" in the package editor. Then load the designtime package, try to compile it, too, and finally install it by clicking "Use" > "Install"; confirm to rebuild the IDE:
RichMemo installs correctly for me following these steps (well, ok - tested only Windows, but I don't see a reason why there should be issues on other widgetsets).