To summarise:

Michael 4 must not be in stalled to the application folder but to an external library folder - the Poser whichever Content folder created by Poser itself on install is best, as there are a lot of files to read and using a later external library will slow things down, but it isn't mandatory.

All morph packs must go to the same location - as WandW says there must be only one /Runtime/Libraries/!DAZ/Michael 4 folder. Content that isn't an ExP Morph expansion can go in other libraries if you like.

Having installed the base and morph packs, and any time you add a new morph pack (or remove an existing pack), you need to run the /Runtime/Libraries/!DAZ/DzCreateExPFiles-m4.bat file to create the "index" files that tells Poser what to load with the figure.

To use the morphs you need to inject them - Pose library Daz's Michael 4>Morph Injections and double-click the packs you want to use.